October 10, 2025 • 30 mins
In this episode of SpaceTime, we uncover the latest revelations in astrophysics, including the intriguing prospect of supermassive dark stars, Australia's ambitious lunar rover mission, and fresh insights into the formation of our solar system.
Supermassive Dark Stars: A New Cosmic Discovery
Astronomers have identified potential candidates for a new type of star in the early universe, known as supermassive dark stars. Recent observations from the Webb Space Telescope suggest that these stars, primarily composed of hydrogen and helium, are supported against gravitational collapse by dark matter. This episode delves into how these dark stars could help explain the existence of supermassive black holes and the unexpectedly bright distant galaxies observed by Webb. With the possibility of a smoking gun signature in their spectra, the implications of this discovery could reshape our understanding of dark matter and stellar evolution.
Australia's Lunar Rover Mission: A Step Towards the Moon
Work is underway on Australia's first lunar rover, set to launch as part of NASA's Artemis programme. This 20-kilogram robotic vehicle, developed by the Queensland University of Technology, will explore lunar geology and contribute to establishing a sustainable human presence on the Moon. The episode covers the rover's design, mission objectives, and the collaborative efforts between Australian institutions and NASA to advance lunar exploration.
Piecing Together the Early Solar System
New research published in Science Advances reveals that the early solar system was more chaotic than previously thought, with planets forming from recycled fragments of shattered bodies rather than pristine materials. This episode discusses the violent origins of our solar system and how high-energy collisions influenced the development of planetary cores, ultimately shaping the celestial bodies we know today.
www.spacetimewithstuartgary.com
✍️ Episode References
Journal of Physical Review Letters
https://journals.aps.org/prl/
Science Advances
https://www.science.org/journal/sciadv
Become a supporter of this podcast: https://www.spreaker.com/podcast/spacetime-your-guide-to-space-astronomy--2458531/support.
Supermassive Dark Stars: A New Cosmic Discovery
Australia's Lunar Rover Mission: A Step Towards the Moon
Piecing Together the Early Solar System
(00:00) The potential discovery of supermassive dark stars
(10:15) Australia's new lunar rover mission details
(18:45) New findings on the chaotic origins of the solar system
(25:30) Skywatch for October: Meteor showers and celestial highlights
Supermassive Dark Stars: A New Cosmic Discovery
Astronomers have identified potential candidates for a new type of star in the early universe, known as supermassive dark stars. Recent observations from the Webb Space Telescope suggest that these stars, primarily composed of hydrogen and helium, are supported against gravitational collapse by dark matter. This episode delves into how these dark stars could help explain the existence of supermassive black holes and the unexpectedly bright distant galaxies observed by Webb. With the possibility of a smoking gun signature in their spectra, the implications of this discovery could reshape our understanding of dark matter and stellar evolution.
Australia's Lunar Rover Mission: A Step Towards the Moon
Work is underway on Australia's first lunar rover, set to launch as part of NASA's Artemis programme. This 20-kilogram robotic vehicle, developed by the Queensland University of Technology, will explore lunar geology and contribute to establishing a sustainable human presence on the Moon. The episode covers the rover's design, mission objectives, and the collaborative efforts between Australian institutions and NASA to advance lunar exploration.
Piecing Together the Early Solar System
New research published in Science Advances reveals that the early solar system was more chaotic than previously thought, with planets forming from recycled fragments of shattered bodies rather than pristine materials. This episode discusses the violent origins of our solar system and how high-energy collisions influenced the development of planetary cores, ultimately shaping the celestial bodies we know today.
www.spacetimewithstuartgary.com
✍️ Episode References
Journal of Physical Review Letters
https://journals.aps.org/prl/
Science Advances
https://www.science.org/journal/sciadv
Become a supporter of this podcast: https://www.spreaker.com/podcast/spacetime-your-guide-to-space-astronomy--2458531/support.
Supermassive Dark Stars: A New Cosmic Discovery
Australia's Lunar Rover Mission: A Step Towards the Moon
Piecing Together the Early Solar System
(00:00) The potential discovery of supermassive dark stars
(10:15) Australia's new lunar rover mission details
(18:45) New findings on the chaotic origins of the solar system
(25:30) Skywatch for October: Meteor showers and celestial highlights
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
This is Spacetime Series twenty eight, episode one hundred and
twenty two, for broadcast on the tenth of October twenty
twenty five. Coming up on space Time, a potential smoking
gun signature for super massive darkstars, Australia's new lunar Rova,
and piecing together the early Solar System. All that and
more coming up on space Time.
Speaker 2 (00:23):
Welcome to space Time with Stuart Gary.
Speaker 1 (00:42):
Astronomers have identified a new type of star in the
very early universe which fits the profile of the long
hypothesized super massive darkstar. If they exist. Darkstars are very
different from the kinds of stars we see in today's universe.
The first stars in the universe, so called Population three stars,
were formed out of the pristine hydrogen and helium created
(01:04):
in the Big Bang thirteen point eight billion years ago.
They were extremely massive, hot blue stars formed in the
first few hundred million years after the Big Bang. They
ended the cosmic dark ages and brought about the epoch
of realization, resulting in the universe we see today. During
their lives, fusing hydrogen and helium on the main sequence,
(01:27):
and when they died, they produced all the other elements
in the cosmos today, but now new observations by the
WEB space telescope have revealed that some of the very
first stars in the cosmos could have been very different
from these regular fusion powered stars. WEB has identified four
extremely distant objects which are consistent both from the point
(01:48):
of view of their observed spectra and morphology, with being
super massive dark stars. The studies authors described super massive
dark stars as extremely bright, giant yet puffy clouds primary
made out of hydrogen and helium, which is supported against
gravitational collapse by the minute amounts of self annihilating dark
matter inside them, hence the term dark stars. These super
(02:11):
massive dark stars and their black hole remnants could be
keys to solving two recent astronomical puzzles, the larger than
expected extremely bright yet compact distant galaxies observed by WEB
and the origin of the super massive black holes powering
the most distant quasars in the universe, black holes which
theoretically didn't have enough time to get that big. One
(02:33):
of the sturdies authors Katherine Freese from the University of
Texas at Austin, developed the original theory behind dark stars
with Doug Spolier and Parlo Gondolo back in two thousand
and eight, which was reported at the time in the
journal Physical Review Letters. In that paper, they envisioned how
dark stars might have led to super massive black holes
(02:53):
in the early universe. Then, in a twenty ten Astrophysical
Journal publication, Freezing colleagues identified two mechanism through which dark
stars could grow to become super massive. They also predicted
that these could seed super massive black holes powering many
The most distinct wasars in the universe. Although dark matter
makes up twenty five percent of the universe, its nature
(03:16):
has continued to elude scientists. They know it exists because
they can see its impact on normal baryonic matter, preventing
galaxies from spinning apart as they rotate and magnifying more
distant objects behind them through gravitational lensing.
Speaker 2 (03:30):
The current thinking is that.
Speaker 1 (03:31):
Dark matter probably consists of a new type of elementary
particle yet to be observed or detected. While the hunter
to text such particles has been on for a few
decades now, no conclusive evidence has ever been found.
Speaker 2 (03:44):
Among the leading candidates for.
Speaker 1 (03:46):
Dark matter are weakly interacting massive particles or whimps. When
they collide, these particles would theoretically annihilate themselves depositing heat
into collapsing clouds of hydrogen and converting them into brightly
shining dark stars. And the conditions for the formation of
dark stars would have been just right a few hundred
million years after the Big Bang at the center of
(04:07):
dark matter Halo's and this is when and where the
first stars in the universe are expected to have formed.
Free says the new WEB observations have now identified spectroscopic
super massive dark star candidates, including the very earliest objects
at redshift fourteen. Now that's just three hundred million years
after the Big Bang, she says, the dark stars would
(04:29):
have had a million times the mass of our sun.
Such early dark stars are important not only in teaching
astronomers about dark matter, but also as precursors for the
early super massive black holes seen by WEB, which would
otherwise be difficult to explain. In the twenty twenty three
PNAS study by Freezing colleagues, the first super massive dark
(04:50):
star candidates jades JZ thirteen zero, Jade's GSZ twelve zero,
and JADE'SJZ eleven zero. We're all identified using furtomture death
from WEBSNEE infrared camera. Since then, spectrum from WEBSNEE Infrared
Spectrographic instrument has provided additional data allowing astronomers to identify
the spectrum morphology of four of the most distant objects
(05:13):
ever seen, including two candidates from that twenty twenty three study.
These include JDASJSZ fourteen zero, JDAS GC fourteen one, JDAS
GC thirteen zero, and jds GZ eleven zero. Each is
consistent with the super massive darkstar interpretation. JDSGC fourteen one
(05:34):
is not resolved, meaning it's consistent with a point source
such as a very distant supermassive.
Speaker 2 (05:39):
Star would be.
Speaker 1 (05:41):
The other three are all extremely compact and can be
modeled by super massive dark stars powering a nebula of
ionized hydrogen and helium surrounding the star. Importantly, dark stars
would have a smirking gun's signature, an absorption feature at
one thousand, six hundred and forty angstrom, due to the
large amounts of singly ironiz helium in their atmospheres, and
(06:02):
in fact, one of the four objects analyzed, JJZ fourteen zero,
does show signs of this feature. Astronomers using ALMA the ATTICAM,
a large millimeter submillimeter array telescope Inicele measured the spectrum
of the same object, revealing the presence of oxygen through
a nebular emission line. The authors say that if both
specual features are confirmed, this object cannot be an isolated
(06:24):
dark star, but rather a dark star embedded in a
metal rich environment, and that could be the outcome of
a merger where a dark matter halo hosting a dark
star merges with a galaxy. Alternatively, dark stars and regular
stars could have formed in the same halo. The identification
of supermassive dark stars would open up the possibility of
(06:45):
learning about dark matter particles based on the observed properties
of those objects, and would establish a new field of astronomy,
the study of dark matter powered stars.
Speaker 2 (06:55):
This is space time.
Speaker 1 (06:57):
Still to come, Australia's new lunar and piecing together the
early Solar System. All that and more still to come
on space time. Works now under way on the Australian
(07:24):
Space Agency ace's first lunar rover mission, which is slated
to launch before the end of the decade. The twenty
kilogram four world robotic vehicle, called the Ruver, would be
used by NASARE as part of its Artemis program. The
study lunar geology, detecting rocks, craters, and other phenomena of interest.
It'll be launched as part of NASA's CT for Commercial
(07:44):
Lunar Payload Services initiative. Once on the Moon's surface, the
roovers expected to be operational for a full lunar day
that's equivalent to fourteen Earth days. Scientists at the Queensland
University of Technology are building the navigation systems for the rover.
They're developing positioning systems that assist the semi autonomous vehicle
to safely explore the lunar surface with limited onboard computing power.
(08:09):
The rover will be designed, built, tested and operated in
Australia through a consultium of industry partners, research organizations, and
ten OSI universities working in partnership with ASA, the Australian
Space Agency. Once launched, it will be remotely operated from
an Australian mission control center and work alongside NASA in
establishing a sustainable human presence on the Moon. As part
(08:32):
of the project, QTS developed a new lunar test center,
which includes an enclosed test bed filled with a lunar
regular simulant designed to replicate the kinds of environment surface
conditions and lighting the vehicle will likely encounter during its
time on the Moon. This is space time still to come.
Piecing together the early Solar System and the constellation of
(08:54):
the Southern Cross.
Speaker 2 (08:55):
The Magellanic clouds.
Speaker 1 (08:57):
And three Medial showers are among the highlight of the
October night skies ont SkyWatch. A new study suggest that
(09:19):
from its earliest period, even before the last of its
protoplanetary nebula gas had been consumed, the Sun's Solar System
and its planets, including the Earth, looked a lot more
like a bin of well used lego blocks than slowly
evolving spheres of untouched elements and minerals. The findings, reported
in the journal Science Advances, suggest that far from being
(09:39):
made of pristine material, the planets were constructed out of
recycled fragments of shattered and rebuilt bodies. The studies lead author,
Damen V. Singh Grew from the l University, says the
research paints a clear picture of the violent origins of
our Solar System. Scientists have long known that in the
earliest days of the Solar System, planets and protoce planets
(10:00):
known as planetesimals formed through a combination of collisions known
as accretion and core formation, which triggered chemical changes in
the cause composition, but the level of influence of each
of these forces has been unknown. Adding to the mystery,
some planetesimals have unusual chemical signatures that would evolve the
presence of highly unlikely metals at the start of a
(10:21):
naturally evolving core formation process.
Speaker 2 (10:24):
Gruel and colleagues say.
Speaker 1 (10:25):
The explanation lies with the smash and rebuild nature of
the early Solar System. For their study, the authors created
simulations of how planetary cause developed in the early years
of the Solar System's formation, based on a reinterpretation of
data taken from iron meteorites thought to be the remnants
of the metallic cause of the first planetesimals. They hypothesized
(10:47):
that high energy collisions began between about one and two
million years after the formation of our Solar System four
point six billion years ago. At that stage, some planet
tesimals had formed metal rich cores, but the wasn't complete.
Collisions shattered these early cause and their fragments later reassembled
themselves into new planetary bodies through acretion. Grul says these
(11:10):
events determine which elements and minerals young worlds carried to
the next stage of planetary formation. The findings showed that
the pathway to planetary formation was far more dynamic and
complex than previously thought.
Speaker 2 (11:23):
This is space time.
Speaker 1 (11:41):
And time now eternalized to the skies and check out
the celestious sphere for October on SkyWatch. October is the
tenth month of the year, and that may seem confusing,
since Octo in Latin means eight rather than ten. The
answer lies in the old Roman calendar, which had just
ten months before the addition of j February, and that
(12:02):
ten month year is still reflected today with the name
September or Septum being Latin for seven October or Octo
meaning eight November and November nine, and December of Desi
meaning ten. Of course, the harlot of October for kids
and those who are young at heart has to be
the last day of the month, celebrated as All Hallows
(12:23):
Evening or Halloween. Halloween is based on ancient Celtic pagan
festivals such as sou Wynn, the Gaelic festival of the Dead.
Soaowyn was eventually christionized by the early Church to become
all saints or Hallow's Eve, or simply Halloween. It's a
time when darkness overtakes the light of day, a reference
(12:43):
to the increasing hours of darkness as the planet's northern
hemisphere moves towards longer winter nights, and so it's a
time when the harvest comes to an end. The increased
hours of darkness mean the boundary between the ward of
the living and the ward of the dead becomes especially thin,
allowing the dead and supernatural to rise in search of
(13:04):
the living, and so the living were disguises so as
not to be recognized by the dead, and it's this
which has led to today's tradition of the Halloween fancy
dress party. In some parts of the world, cross dressing
is popular on Halloween, a reflection of the secret desires
and fantasies of their pagan ancestors. Sometimes not so Many
generations removed to ensure that crops and livestock survive the
(13:28):
cold winter months ahead, Offerings of food and drink would
be left outside for the spirits and fairies of the
other side, and it was this which automately led to
today's practice of trek or treat. Also, candles would be
lit and prayers offered to the souls of the dead,
as Halloween was a time when the spirits of the
dead would return to their former homes. Special bonfires were
(13:50):
also lit on Halloween to light the darkness, thereby preventing
souls of the dead from returning and keeping the evil way.
The flames, smirk and ashes were deemed to have protective
and cleansing powers and we use for diviniation. As for
the tradition of carving pumpkins and the jack o' lanterns, well,
that was originally meant either to represent spirits or supernatural beings,
(14:13):
or alternatively to ward off evil spirits. In many parts
of the world, the Christian religious observances of All Hallows
Eve include attending church services and lighting candles on the
graves of the dead, and Christians historically abstained from eating
meat on All Hallows Eve, a tradition reflected in the
eating of certain vegetable foods on the day, including apples, poteta, pancakes,
(14:36):
and sal cakes. Apple bobbing originated because the apple was
a Celtic symbol of love, and so grabbing the apple
with your teeth had certain erotic overtones. Halloween is a
time of fortune telling, and divination games, playing pranks to
scare people, visiting haunted attractions, telling scary stories, and of course,
(14:57):
watching horror movies. Looking to the southwest, you'll see the
two bright point of stars which show the weight of
the Southern Cross. The brightest and what also looks like
the more distant of the two stars from the Southern
Cross is Alpha Centauri, which is actually the nearest star
system to our own solar system. Alpha Centauri is a
(15:17):
triple star system comprising two stars Alpha Centaury a and B,
which orbit each other in a binary and a third star,
Proximate Centaury, which orbit the pair like the Sun. Alpha
Centauri A is a spectrotype G yellow dwarf star. It's
about ten percent more massive than our Sun and about
one and a half times as luminous. Astronomers describe stars
(15:40):
in terms of spectral types. It's a classification system based
on temperature and characteristics. The hottest, most massive, and most
luminous stars are known as spectrotype O blue stars. They're
followed by specturotype B blue white stars, then spectro type
A white starsal type F whitish yellow stars, spectual type
(16:03):
G yellow stars. That's where our Sun fits in spectual
type K orange stars, and the coolest and least massive
stars of all are the spectual type M red stars.
Each spetual classification is also subdivided using a numeric digit
to represent temperature, with zero being the hardest, deny in
the coolest, and a Roman numeral to represent luminosity. Now
(16:25):
you pull of that together and our Sun becomes a
G two V or G two five yellow dwarf star.
Also included in the stellar classification system are special types
LT and Y, which are assigned to failed stars known
as brown dwarves, some of which were actually born as
spectual type M red stars but became brown dwarves after
(16:46):
losing some of their mass. Brown dwarves fit into a
unique category between the largest planets, which can be up
to thirteen times the mass of Jupiter, and the smaller stars,
those spetual type M red dwarf stars we mentioned earlier.
These can be seventy five to eighty times the mass
of Jupiter or about zero point zero eight solar masses.
(17:08):
Alphicentury a's binary partner, Alphaicentury B, is a speciotype K
orange dwarf star, a little smaller and cooler than its
companion with about ninety percent of the Sun's mass and
about half its luminosity. This binary pair, alphaicentaury A and
B orbit each other at between eleven point two and
thirty five point six astronomical units. An astronomical unit is
(17:32):
the average distance between the Earth and the Sun, which
equates to about one hundred and fifty million kilometers or
around eight point three line minutes. So the pairs orbit
around each other varies by between the average distance between
the Sun and Satin and between the Sun and Pluto.
It takes the two stars seventy nine point nine to
one earth years to complete each orbit. On average, alphicentaury
(17:56):
A and B are located four point three seven light
years from this Sun.
Speaker 2 (18:01):
Now.
Speaker 1 (18:01):
Although a light year sounds like a measure of time,
it's actually a measure of distance. A light year is
the distance of about ten trillion kilometers. That's the distance
of photon can travel in a year at the speed
of light, which is around three hundred thousand kilometers per
second in a vacuum, and the ultimate speed limit of
the universe. The third star in the Alpha Centaury system
(18:22):
is a spectrotype m red dwarf start named Proxima Centaury.
Right now, Proxima Centaury is just four point twenty five
light years away, making it the nearest start of the
Earth other than the Sun. It is only loosely gravitationally
bound to Alpha centaury A and B, orbiting the pair
at an average distance of thirteen thousand astronomical units or
(18:44):
around zero point two one light years. That's about four
hundred and thirty times the size of Neptune's thirty astronomical
unit orbit around the Sun. In twenty sixteen, astronomers confirm
the existence of an Earth sized terrestrial planet orbiting within
the habitable zone of Proxmasentori, making it the nearest known
extra sol or exo planet to Earth. The habitable zone,
(19:06):
which is sometimes also referred to as the Gaudylock zone,
is that area out from a star where it's not
too hot, not too cold, but just right for liquid water,
central for life as we know it to exist on
the planet's surface. The planet, known its Proxima B, takes
just eleven Earth days to complete one orbit around its
host star. That's far close to the mercury's eighty eight
(19:29):
earth day orbit around the Sun. A few years ago,
A second, more distant planet, Proximus C, was also discovered
orbiting around the star, but well outside its habitable zone.
The second and slightly fainter of the two pointer stars
is Bitter Centaury, and while Alpha Centauri is the third
brightest star in the night sky, outshone only by Sirius
(19:52):
in Canopus, Bitter Centauri is only about the tenth brightest.
Looking to the southeast and you'll see the bright blue
white star Alpha Ridney or Akinar, which represents the southern
tip of Eridanus, one of the largest and longest constellations
in the sky. Akinar is located about one hundred and
thirty nine light years away. It's actually a binary star
(20:14):
system comprising two stars, Alpha Ridney A and Alpha Ridney B.
Alpha Ridney A is a high, young spirtual type B
blue star. It has about six point seven times the
mass of the Sun and is stunning three than one
hundred and fifty times the Sun's luminosity. By comparison, the
companion star Alpha Ridney B appears to be a spectrotype
(20:35):
A white star with about twice the Sun's mass. The
two stars orbit each other every fourteen to fifteen earth
years at an average distance of about twelve point three
astronomical units. Because of its high rotation rate of over
sixteen kilometres per second, Alpha Aridney as actually one of
the least spherical stars in the Milky Way, spinning so rapidly,
(20:57):
it's assumed the shape of an obleque sphere with an
equatorial diameter fifty six percent greater than its polar diameter.
This distorted shape means the star displays a significant latitudinal temperature,
with its polar temperature being about twenty thousand kelvin, while
it's equatorial temperature is only around ten thousand kelvin. That's
because it's much further away from its stellar core. The
(21:20):
high polar temperatures are generating a fast polar wind that's
ejecting matter from the star and creating spectacular polar envelope
of hot gas and plasma. Now, if you look up
between the south celestial poland Akina from a really dark place,
you'll see two faint, fuzzy looking clouds. Now, these aren't
(21:40):
actually clouds. They are two satellite dwarf galaxies which are
but the Milky Way, known as the Large and Small
Magillani Clouds. They're named after Ferdinand Magellan, who became the
first European to officially record them during his expedition to
circumnavigate the Earth between fifteen nineteen and fifteen twenty two.
The bigger and nearer of the pair is the large
(22:03):
Magellanic Cloud, which is located around one hundred and sixty
light years away. It's easier to spot about halfway between
Akinar and the horizon. It's about fourteen thousand light years across,
twice that of the small Magellanic Cloud, which is located
a more distant two hundred thousand light years from the
Milky Way. Now, by comparison to these two satellite galaxies,
(22:25):
the Milky Way is huge one hundred thousand light years across.
These two dwarf galaxies are separated from each other by
roughly seventy five thousand light years. The Magellanic clouds were
considered the closest galaxies to the Milky Way until the
nineteen ninety four discovery of the Sagittarius dwarf elliptical galaxy
and the two thousand and three confirmation that the Canis
(22:46):
major dwarf galaxy is actually Ourneares s galactic neighbor. The
total mass of the Magellanic clouds is uncertain. Only a
fraction of their gas seems to have coalesced into stars.
They also probably both have very large dark matter halos. Still,
one recent estimate places the total mass of the large
Magellanic cloud at about one tenth out of the Milky Way.
(23:07):
The Magellanic clouds of both being greatly distorted by gravitational
tidal interactions as they're gradually torn apart and absorbed by
the Milky Way. These huge tidal forces have turned both
Magellanic clouds into irregular, disrupted buds spiral galaxies. The large
Magilani cloud still retains a very clear spiral structure, at
(23:29):
least in radio telescope images of neutral hydrogen. But gravity
isn't a one way street, and the combined gravitational force
of both Magileni clouds is also affecting the Milky Way,
distorting the outer parts of our galactic disk. And there
are streams of neutral hydrogen gas clouds and isolated stars
connecting both dwarf galaxies to each other and to the
(23:51):
Milky Way, a brilliant example of galactic cannibalism at work. Now,
if you look just above the small magellanic cloud. Using
a backyard telescope or a good pair of binoculars, you'll
see a small blurry dot that is the forty seven
to Canna globular cluster, a tightly packed ball of stars
some sixteen thousand light is away. They were all originally
(24:13):
formed at the same time through the gravitational collapse of
the same molecular gas and dust cloud. If you look
to the west, you'll see the bright reddish iron supergiant
star and Taris the heart of the constellation Scorpius, the Scorpion,
and above it you'll see a bunch of stars stretching
out shaped like a reverse question mark. That's the tail
(24:33):
of the Scorpion. Now just above and to the north
is the constellation Sagittarius, the archer. Sagittarius shows the weight
to the super massive black hole at the center of
the Milky Way galaxy some twenty seven thousand light is away.
This monster black hole, known as Sagittarius a star, has
about four point three million times the mass of our Sun. Now,
(24:57):
looking to the north northwest this time of the year,
see the constellation Lyra the harp and its brighter star Vega,
the fifth brighter star in the night sky, and one
of the closest are just twenty five light years away.
Vega is a special type, a white star, more than
twice the size and some forty times the mass of
our Sun. Now just to the right of Lyra and
(25:19):
almost directly north, just above the horizon is the constellation
of Signus the Swan and its sprider star Deneb, one
of the most luminous stars in the sky. Deneb is
a massive spectrotype, a white super giant, some nineteen times
the mass and over one hundred times that I am
of the Sun. The star is somewhere between fifty five
(25:40):
thousand and one hundred and ninety six thousand times as
luminous as the Sun. The huge range in luminosity estimate
is caused by the difficult in determining Deneb's exact distance
from US. Science's best estimates place it somewhere around twenty
six hundred light years away, give or take two hundred
and twelve light years high. In the northern sky right
(26:00):
now is the constellation Aquilla the Eagle and its spider
star all Tair. Altair is another spectrotype, a white star,
but located a lot closer just seventeen light years away.
It's about ten times brighter than the Sun, with about
one point eight nine times the Sun's mass. Despite its size,
Altear spins on its axis in just ten hours, compared
(26:23):
to our Sun's twenty eight earth day rotation. Now, these
three stars Alte Denebinvega forms stillar grouping known as the
Summer Triangle.
Speaker 2 (26:34):
Now.
Speaker 1 (26:34):
Also in October, there are three meteor showers, the Draconids,
the Taurreds, and the Orionids. The Dracernids take place on
October the eighth. They're so named because the meteors appear
to radiate out from the constellation Draco the Dragon, and
so are best viewed from the northern Hemisphere. They're actually
(26:54):
produced as the Earth's orbit takes it through the debris
trail left behind by the comet twenty one p chrkobini Zina,
which takes about six point six earth years to make
a single.
Speaker 2 (27:05):
Revolution of the Sun.
Speaker 1 (27:07):
The Torred's media shower takes place on October tenth, and,
as their name suggests, they appear to radiate out from
the constellation Taurus the Ball. Their mediors are composed of
larger than average pebbles, and dust grains, and are thought
to be generated by a debris left behind by the
comet two p Anki, although it's thought that both the
Torreds and Anchi could be the remains of an earlier
(27:29):
comet which disintegrated over the past twenty thousand to thirty
thousand years, breaking into several pieces and releasing material both
by normal cometary activity and possibly also by gravitational title
interactions with the Earth and other planets. The Torred's debris
stream is the largest in the Inner Solar System, taking
the Earth several weeks to pass through and resulting in
(27:51):
an extended period of media activity compared to other meteor showers,
which are usually over in just a matter of days. Now,
due to the gravitational perturbations planets, especially Jupiter, the Tourreds
have been spread out over time, allowing separate segments labeled
the Northern Toureds and Southern Torereads to be observable at
different times in different hemispheres. The Southern Tourreds are active
(28:13):
from around September tenth to November twentieth, while the Northern
Tourreds are active from October the twentieth to December tenth.
The third medior shower this month is the Orionids, which
peak on October the twentieth. They're caused by debris from
the Comet Halley, which also causes the Etta Accuridz media
shower in May. Commet Halley takes seventy six years to
(28:34):
complete each orbit around the Sun. It'll next become visible
near Earth in twenty sixty one. The Orionids are equally
spectacular in both northern and southern Hemisphere skies, with up
to twenty meteors an hour radiating out from the constellation Orion.
The best time to see the Orionids is just after
midnight and ripe before dusk. This is Spacetime and that's
(29:13):
the show for now. Spacetime is available every Monday, Wednesday
and Friday through Apple Podcasts, iTunes, Stitcher, Google podcast, pocker Casts, Spotify, Acast,
Amazon Music, Bites, dot Com, SoundCloud, YouTube, your favorite podcast
download provider, and from space Time with Stuart Gary dot com.
(29:34):
Space Time's also broadcast through the National Science Foundation, on
Science Own Radio and on both iHeartRadio and tune In Radio.
And you can help to support our show by visiting
the Spacetime store for a range of promotional merchandising goodies,
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to triple episode commercial free versions of the show, as
(29:55):
well as lots of burness audio content which doesn't go
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Just go to space Time with Stewart Gary dot com
for full details.
Speaker 2 (30:06):
You've been listening to space Time with Stuart Garry.
Speaker 1 (30:09):
This has been another quality podcast production from bytes dot com.
This is Spacetime Series twenty eight, episode one hundred and
twenty two, for broadcast on the tenth of October twenty
twenty five. Coming up on space Time, a potential smoking
gun signature for super massive darkstars, Australia's new lunar Rova,
and piecing together the early Solar System. All that and
more coming up on space Time.
Speaker 2 (00:23):
Welcome to space Time with Stuart Gary.
Speaker 1 (00:42):
Astronomers have identified a new type of star in the
very early universe which fits the profile of the long
hypothesized super massive darkstar. If they exist. Darkstars are very
different from the kinds of stars we see in today's universe.
The first stars in the universe, so called Population three stars,
were formed out of the pristine hydrogen and helium created
(01:04):
in the Big Bang thirteen point eight billion years ago.
They were extremely massive, hot blue stars formed in the
first few hundred million years after the Big Bang. They
ended the cosmic dark ages and brought about the epoch
of realization, resulting in the universe we see today. During
their lives, fusing hydrogen and helium on the main sequence,
(01:27):
and when they died, they produced all the other elements
in the cosmos today, but now new observations by the
WEB space telescope have revealed that some of the very
first stars in the cosmos could have been very different
from these regular fusion powered stars. WEB has identified four
extremely distant objects which are consistent both from the point
(01:48):
of view of their observed spectra and morphology, with being
super massive dark stars. The studies authors described super massive
dark stars as extremely bright, giant yet puffy clouds primary
made out of hydrogen and helium, which is supported against
gravitational collapse by the minute amounts of self annihilating dark
matter inside them, hence the term dark stars. These super
(02:11):
massive dark stars and their black hole remnants could be
keys to solving two recent astronomical puzzles, the larger than
expected extremely bright yet compact distant galaxies observed by WEB
and the origin of the super massive black holes powering
the most distant quasars in the universe, black holes which
theoretically didn't have enough time to get that big. One
(02:33):
of the sturdies authors Katherine Freese from the University of
Texas at Austin, developed the original theory behind dark stars
with Doug Spolier and Parlo Gondolo back in two thousand
and eight, which was reported at the time in the
journal Physical Review Letters. In that paper, they envisioned how
dark stars might have led to super massive black holes
(02:53):
in the early universe. Then, in a twenty ten Astrophysical
Journal publication, Freezing colleagues identified two mechanism through which dark
stars could grow to become super massive. They also predicted
that these could seed super massive black holes powering many
The most distinct wasars in the universe. Although dark matter
makes up twenty five percent of the universe, its nature
(03:16):
has continued to elude scientists. They know it exists because
they can see its impact on normal baryonic matter, preventing
galaxies from spinning apart as they rotate and magnifying more
distant objects behind them through gravitational lensing.
Speaker 2 (03:30):
The current thinking is that.
Speaker 1 (03:31):
Dark matter probably consists of a new type of elementary
particle yet to be observed or detected. While the hunter
to text such particles has been on for a few
decades now, no conclusive evidence has ever been found.
Speaker 2 (03:44):
Among the leading candidates for.
Speaker 1 (03:46):
Dark matter are weakly interacting massive particles or whimps. When
they collide, these particles would theoretically annihilate themselves depositing heat
into collapsing clouds of hydrogen and converting them into brightly
shining dark stars. And the conditions for the formation of
dark stars would have been just right a few hundred
million years after the Big Bang at the center of
(04:07):
dark matter Halo's and this is when and where the
first stars in the universe are expected to have formed.
Free says the new WEB observations have now identified spectroscopic
super massive dark star candidates, including the very earliest objects
at redshift fourteen. Now that's just three hundred million years
after the Big Bang, she says, the dark stars would
(04:29):
have had a million times the mass of our sun.
Such early dark stars are important not only in teaching
astronomers about dark matter, but also as precursors for the
early super massive black holes seen by WEB, which would
otherwise be difficult to explain. In the twenty twenty three
PNAS study by Freezing colleagues, the first super massive dark
(04:50):
star candidates jades JZ thirteen zero, Jade's GSZ twelve zero,
and JADE'SJZ eleven zero. We're all identified using furtomture death
from WEBSNEE infrared camera. Since then, spectrum from WEBSNEE Infrared
Spectrographic instrument has provided additional data allowing astronomers to identify
the spectrum morphology of four of the most distant objects
(05:13):
ever seen, including two candidates from that twenty twenty three study.
These include JDASJSZ fourteen zero, JDAS GC fourteen one, JDAS
GC thirteen zero, and jds GZ eleven zero. Each is
consistent with the super massive darkstar interpretation. JDSGC fourteen one
(05:34):
is not resolved, meaning it's consistent with a point source
such as a very distant supermassive.
Speaker 2 (05:39):
Star would be.
Speaker 1 (05:41):
The other three are all extremely compact and can be
modeled by super massive dark stars powering a nebula of
ionized hydrogen and helium surrounding the star. Importantly, dark stars
would have a smirking gun's signature, an absorption feature at
one thousand, six hundred and forty angstrom, due to the
large amounts of singly ironiz helium in their atmospheres, and
(06:02):
in fact, one of the four objects analyzed, JJZ fourteen zero,
does show signs of this feature. Astronomers using ALMA the ATTICAM,
a large millimeter submillimeter array telescope Inicele measured the spectrum
of the same object, revealing the presence of oxygen through
a nebular emission line. The authors say that if both
specual features are confirmed, this object cannot be an isolated
(06:24):
dark star, but rather a dark star embedded in a
metal rich environment, and that could be the outcome of
a merger where a dark matter halo hosting a dark
star merges with a galaxy. Alternatively, dark stars and regular
stars could have formed in the same halo. The identification
of supermassive dark stars would open up the possibility of
(06:45):
learning about dark matter particles based on the observed properties
of those objects, and would establish a new field of astronomy,
the study of dark matter powered stars.
Speaker 2 (06:55):
This is space time.
Speaker 1 (06:57):
Still to come, Australia's new lunar and piecing together the
early Solar System. All that and more still to come
on space time. Works now under way on the Australian
(07:24):
Space Agency ace's first lunar rover mission, which is slated
to launch before the end of the decade. The twenty
kilogram four world robotic vehicle, called the Ruver, would be
used by NASARE as part of its Artemis program. The
study lunar geology, detecting rocks, craters, and other phenomena of interest.
It'll be launched as part of NASA's CT for Commercial
(07:44):
Lunar Payload Services initiative. Once on the Moon's surface, the
roovers expected to be operational for a full lunar day
that's equivalent to fourteen Earth days. Scientists at the Queensland
University of Technology are building the navigation systems for the rover.
They're developing positioning systems that assist the semi autonomous vehicle
to safely explore the lunar surface with limited onboard computing power.
(08:09):
The rover will be designed, built, tested and operated in
Australia through a consultium of industry partners, research organizations, and
ten OSI universities working in partnership with ASA, the Australian
Space Agency. Once launched, it will be remotely operated from
an Australian mission control center and work alongside NASA in
establishing a sustainable human presence on the Moon. As part
(08:32):
of the project, QTS developed a new lunar test center,
which includes an enclosed test bed filled with a lunar
regular simulant designed to replicate the kinds of environment surface
conditions and lighting the vehicle will likely encounter during its
time on the Moon. This is space time still to come.
Piecing together the early Solar System and the constellation of
(08:54):
the Southern Cross.
Speaker 2 (08:55):
The Magellanic clouds.
Speaker 1 (08:57):
And three Medial showers are among the highlight of the
October night skies ont SkyWatch. A new study suggest that
(09:19):
from its earliest period, even before the last of its
protoplanetary nebula gas had been consumed, the Sun's Solar System
and its planets, including the Earth, looked a lot more
like a bin of well used lego blocks than slowly
evolving spheres of untouched elements and minerals. The findings, reported
in the journal Science Advances, suggest that far from being
(09:39):
made of pristine material, the planets were constructed out of
recycled fragments of shattered and rebuilt bodies. The studies lead author,
Damen V. Singh Grew from the l University, says the
research paints a clear picture of the violent origins of
our Solar System. Scientists have long known that in the
earliest days of the Solar System, planets and protoce planets
(10:00):
known as planetesimals formed through a combination of collisions known
as accretion and core formation, which triggered chemical changes in
the cause composition, but the level of influence of each
of these forces has been unknown. Adding to the mystery,
some planetesimals have unusual chemical signatures that would evolve the
presence of highly unlikely metals at the start of a
(10:21):
naturally evolving core formation process.
Speaker 2 (10:24):
Gruel and colleagues say.
Speaker 1 (10:25):
The explanation lies with the smash and rebuild nature of
the early Solar System. For their study, the authors created
simulations of how planetary cause developed in the early years
of the Solar System's formation, based on a reinterpretation of
data taken from iron meteorites thought to be the remnants
of the metallic cause of the first planetesimals. They hypothesized
(10:47):
that high energy collisions began between about one and two
million years after the formation of our Solar System four
point six billion years ago. At that stage, some planet
tesimals had formed metal rich cores, but the wasn't complete.
Collisions shattered these early cause and their fragments later reassembled
themselves into new planetary bodies through acretion. Grul says these
(11:10):
events determine which elements and minerals young worlds carried to
the next stage of planetary formation. The findings showed that
the pathway to planetary formation was far more dynamic and
complex than previously thought.
Speaker 2 (11:23):
This is space time.
Speaker 1 (11:41):
And time now eternalized to the skies and check out
the celestious sphere for October on SkyWatch. October is the
tenth month of the year, and that may seem confusing,
since Octo in Latin means eight rather than ten. The
answer lies in the old Roman calendar, which had just
ten months before the addition of j February, and that
(12:02):
ten month year is still reflected today with the name
September or Septum being Latin for seven October or Octo
meaning eight November and November nine, and December of Desi
meaning ten. Of course, the harlot of October for kids
and those who are young at heart has to be
the last day of the month, celebrated as All Hallows
(12:23):
Evening or Halloween. Halloween is based on ancient Celtic pagan
festivals such as sou Wynn, the Gaelic festival of the Dead.
Soaowyn was eventually christionized by the early Church to become
all saints or Hallow's Eve, or simply Halloween. It's a
time when darkness overtakes the light of day, a reference
(12:43):
to the increasing hours of darkness as the planet's northern
hemisphere moves towards longer winter nights, and so it's a
time when the harvest comes to an end. The increased
hours of darkness mean the boundary between the ward of
the living and the ward of the dead becomes especially thin,
allowing the dead and supernatural to rise in search of
(13:04):
the living, and so the living were disguises so as
not to be recognized by the dead, and it's this
which has led to today's tradition of the Halloween fancy
dress party. In some parts of the world, cross dressing
is popular on Halloween, a reflection of the secret desires
and fantasies of their pagan ancestors. Sometimes not so Many
generations removed to ensure that crops and livestock survive the
(13:28):
cold winter months ahead, Offerings of food and drink would
be left outside for the spirits and fairies of the
other side, and it was this which automately led to
today's practice of trek or treat. Also, candles would be
lit and prayers offered to the souls of the dead,
as Halloween was a time when the spirits of the
dead would return to their former homes. Special bonfires were
(13:50):
also lit on Halloween to light the darkness, thereby preventing
souls of the dead from returning and keeping the evil way.
The flames, smirk and ashes were deemed to have protective
and cleansing powers and we use for diviniation. As for
the tradition of carving pumpkins and the jack o' lanterns, well,
that was originally meant either to represent spirits or supernatural beings,
(14:13):
or alternatively to ward off evil spirits. In many parts
of the world, the Christian religious observances of All Hallows
Eve include attending church services and lighting candles on the
graves of the dead, and Christians historically abstained from eating
meat on All Hallows Eve, a tradition reflected in the
eating of certain vegetable foods on the day, including apples, poteta, pancakes,
(14:36):
and sal cakes. Apple bobbing originated because the apple was
a Celtic symbol of love, and so grabbing the apple
with your teeth had certain erotic overtones. Halloween is a
time of fortune telling, and divination games, playing pranks to
scare people, visiting haunted attractions, telling scary stories, and of course,
(14:57):
watching horror movies. Looking to the southwest, you'll see the
two bright point of stars which show the weight of
the Southern Cross. The brightest and what also looks like
the more distant of the two stars from the Southern
Cross is Alpha Centauri, which is actually the nearest star
system to our own solar system. Alpha Centauri is a
(15:17):
triple star system comprising two stars Alpha Centaury a and B,
which orbit each other in a binary and a third star,
Proximate Centaury, which orbit the pair like the Sun. Alpha
Centauri A is a spectrotype G yellow dwarf star. It's
about ten percent more massive than our Sun and about
one and a half times as luminous. Astronomers describe stars
(15:40):
in terms of spectral types. It's a classification system based
on temperature and characteristics. The hottest, most massive, and most
luminous stars are known as spectrotype O blue stars. They're
followed by specturotype B blue white stars, then spectro type
A white starsal type F whitish yellow stars, spectual type
(16:03):
G yellow stars. That's where our Sun fits in spectual
type K orange stars, and the coolest and least massive
stars of all are the spectual type M red stars.
Each spetual classification is also subdivided using a numeric digit
to represent temperature, with zero being the hardest, deny in
the coolest, and a Roman numeral to represent luminosity. Now
(16:25):
you pull of that together and our Sun becomes a
G two V or G two five yellow dwarf star.
Also included in the stellar classification system are special types
LT and Y, which are assigned to failed stars known
as brown dwarves, some of which were actually born as
spectual type M red stars but became brown dwarves after
(16:46):
losing some of their mass. Brown dwarves fit into a
unique category between the largest planets, which can be up
to thirteen times the mass of Jupiter, and the smaller stars,
those spetual type M red dwarf stars we mentioned earlier.
These can be seventy five to eighty times the mass
of Jupiter or about zero point zero eight solar masses.
(17:08):
Alphicentury a's binary partner, Alphaicentury B, is a speciotype K
orange dwarf star, a little smaller and cooler than its
companion with about ninety percent of the Sun's mass and
about half its luminosity. This binary pair, alphaicentaury A and
B orbit each other at between eleven point two and
thirty five point six astronomical units. An astronomical unit is
(17:32):
the average distance between the Earth and the Sun, which
equates to about one hundred and fifty million kilometers or
around eight point three line minutes. So the pairs orbit
around each other varies by between the average distance between
the Sun and Satin and between the Sun and Pluto.
It takes the two stars seventy nine point nine to
one earth years to complete each orbit. On average, alphicentaury
(17:56):
A and B are located four point three seven light
years from this Sun.
Speaker 2 (18:01):
Now.
Speaker 1 (18:01):
Although a light year sounds like a measure of time,
it's actually a measure of distance. A light year is
the distance of about ten trillion kilometers. That's the distance
of photon can travel in a year at the speed
of light, which is around three hundred thousand kilometers per
second in a vacuum, and the ultimate speed limit of
the universe. The third star in the Alpha Centaury system
(18:22):
is a spectrotype m red dwarf start named Proxima Centaury.
Right now, Proxima Centaury is just four point twenty five
light years away, making it the nearest start of the
Earth other than the Sun. It is only loosely gravitationally
bound to Alpha centaury A and B, orbiting the pair
at an average distance of thirteen thousand astronomical units or
(18:44):
around zero point two one light years. That's about four
hundred and thirty times the size of Neptune's thirty astronomical
unit orbit around the Sun. In twenty sixteen, astronomers confirm
the existence of an Earth sized terrestrial planet orbiting within
the habitable zone of Proxmasentori, making it the nearest known
extra sol or exo planet to Earth. The habitable zone,
(19:06):
which is sometimes also referred to as the Gaudylock zone,
is that area out from a star where it's not
too hot, not too cold, but just right for liquid water,
central for life as we know it to exist on
the planet's surface. The planet, known its Proxima B, takes
just eleven Earth days to complete one orbit around its
host star. That's far close to the mercury's eighty eight
(19:29):
earth day orbit around the Sun. A few years ago,
A second, more distant planet, Proximus C, was also discovered
orbiting around the star, but well outside its habitable zone.
The second and slightly fainter of the two pointer stars
is Bitter Centaury, and while Alpha Centauri is the third
brightest star in the night sky, outshone only by Sirius
(19:52):
in Canopus, Bitter Centauri is only about the tenth brightest.
Looking to the southeast and you'll see the bright blue
white star Alpha Ridney or Akinar, which represents the southern
tip of Eridanus, one of the largest and longest constellations
in the sky. Akinar is located about one hundred and
thirty nine light years away. It's actually a binary star
(20:14):
system comprising two stars, Alpha Ridney A and Alpha Ridney B.
Alpha Ridney A is a high, young spirtual type B
blue star. It has about six point seven times the
mass of the Sun and is stunning three than one
hundred and fifty times the Sun's luminosity. By comparison, the
companion star Alpha Ridney B appears to be a spectrotype
(20:35):
A white star with about twice the Sun's mass. The
two stars orbit each other every fourteen to fifteen earth
years at an average distance of about twelve point three
astronomical units. Because of its high rotation rate of over
sixteen kilometres per second, Alpha Aridney as actually one of
the least spherical stars in the Milky Way, spinning so rapidly,
(20:57):
it's assumed the shape of an obleque sphere with an
equatorial diameter fifty six percent greater than its polar diameter.
This distorted shape means the star displays a significant latitudinal temperature,
with its polar temperature being about twenty thousand kelvin, while
it's equatorial temperature is only around ten thousand kelvin. That's
because it's much further away from its stellar core. The
(21:20):
high polar temperatures are generating a fast polar wind that's
ejecting matter from the star and creating spectacular polar envelope
of hot gas and plasma. Now, if you look up
between the south celestial poland Akina from a really dark place,
you'll see two faint, fuzzy looking clouds. Now, these aren't
(21:40):
actually clouds. They are two satellite dwarf galaxies which are
but the Milky Way, known as the Large and Small
Magillani Clouds. They're named after Ferdinand Magellan, who became the
first European to officially record them during his expedition to
circumnavigate the Earth between fifteen nineteen and fifteen twenty two.
The bigger and nearer of the pair is the large
(22:03):
Magellanic Cloud, which is located around one hundred and sixty
light years away. It's easier to spot about halfway between
Akinar and the horizon. It's about fourteen thousand light years across,
twice that of the small Magellanic Cloud, which is located
a more distant two hundred thousand light years from the
Milky Way. Now, by comparison to these two satellite galaxies,
(22:25):
the Milky Way is huge one hundred thousand light years across.
These two dwarf galaxies are separated from each other by
roughly seventy five thousand light years. The Magellanic clouds were
considered the closest galaxies to the Milky Way until the
nineteen ninety four discovery of the Sagittarius dwarf elliptical galaxy
and the two thousand and three confirmation that the Canis
(22:46):
major dwarf galaxy is actually Ourneares s galactic neighbor. The
total mass of the Magellanic clouds is uncertain. Only a
fraction of their gas seems to have coalesced into stars.
They also probably both have very large dark matter halos. Still,
one recent estimate places the total mass of the large
Magellanic cloud at about one tenth out of the Milky Way.
(23:07):
The Magellanic clouds of both being greatly distorted by gravitational
tidal interactions as they're gradually torn apart and absorbed by
the Milky Way. These huge tidal forces have turned both
Magellanic clouds into irregular, disrupted buds spiral galaxies. The large
Magilani cloud still retains a very clear spiral structure, at
(23:29):
least in radio telescope images of neutral hydrogen. But gravity
isn't a one way street, and the combined gravitational force
of both Magileni clouds is also affecting the Milky Way,
distorting the outer parts of our galactic disk. And there
are streams of neutral hydrogen gas clouds and isolated stars
connecting both dwarf galaxies to each other and to the
(23:51):
Milky Way, a brilliant example of galactic cannibalism at work. Now,
if you look just above the small magellanic cloud. Using
a backyard telescope or a good pair of binoculars, you'll
see a small blurry dot that is the forty seven
to Canna globular cluster, a tightly packed ball of stars
some sixteen thousand light is away. They were all originally
(24:13):
formed at the same time through the gravitational collapse of
the same molecular gas and dust cloud. If you look
to the west, you'll see the bright reddish iron supergiant
star and Taris the heart of the constellation Scorpius, the Scorpion,
and above it you'll see a bunch of stars stretching
out shaped like a reverse question mark. That's the tail
(24:33):
of the Scorpion. Now just above and to the north
is the constellation Sagittarius, the archer. Sagittarius shows the weight
to the super massive black hole at the center of
the Milky Way galaxy some twenty seven thousand light is away.
This monster black hole, known as Sagittarius a star, has
about four point three million times the mass of our Sun. Now,
(24:57):
looking to the north northwest this time of the year,
see the constellation Lyra the harp and its brighter star Vega,
the fifth brighter star in the night sky, and one
of the closest are just twenty five light years away.
Vega is a special type, a white star, more than
twice the size and some forty times the mass of
our Sun. Now just to the right of Lyra and
(25:19):
almost directly north, just above the horizon is the constellation
of Signus the Swan and its sprider star Deneb, one
of the most luminous stars in the sky. Deneb is
a massive spectrotype, a white super giant, some nineteen times
the mass and over one hundred times that I am
of the Sun. The star is somewhere between fifty five
(25:40):
thousand and one hundred and ninety six thousand times as
luminous as the Sun. The huge range in luminosity estimate
is caused by the difficult in determining Deneb's exact distance
from US. Science's best estimates place it somewhere around twenty
six hundred light years away, give or take two hundred
and twelve light years high. In the northern sky right
(26:00):
now is the constellation Aquilla the Eagle and its spider
star all Tair. Altair is another spectrotype, a white star,
but located a lot closer just seventeen light years away.
It's about ten times brighter than the Sun, with about
one point eight nine times the Sun's mass. Despite its size,
Altear spins on its axis in just ten hours, compared
(26:23):
to our Sun's twenty eight earth day rotation. Now, these
three stars Alte Denebinvega forms stillar grouping known as the
Summer Triangle.
Speaker 2 (26:34):
Now.
Speaker 1 (26:34):
Also in October, there are three meteor showers, the Draconids,
the Taurreds, and the Orionids. The Dracernids take place on
October the eighth. They're so named because the meteors appear
to radiate out from the constellation Draco the Dragon, and
so are best viewed from the northern Hemisphere. They're actually
(26:54):
produced as the Earth's orbit takes it through the debris
trail left behind by the comet twenty one p chrkobini Zina,
which takes about six point six earth years to make
a single.
Speaker 2 (27:05):
Revolution of the Sun.
Speaker 1 (27:07):
The Torred's media shower takes place on October tenth, and,
as their name suggests, they appear to radiate out from
the constellation Taurus the Ball. Their mediors are composed of
larger than average pebbles, and dust grains, and are thought
to be generated by a debris left behind by the
comet two p Anki, although it's thought that both the
Torreds and Anchi could be the remains of an earlier
(27:29):
comet which disintegrated over the past twenty thousand to thirty
thousand years, breaking into several pieces and releasing material both
by normal cometary activity and possibly also by gravitational title
interactions with the Earth and other planets. The Torred's debris
stream is the largest in the Inner Solar System, taking
the Earth several weeks to pass through and resulting in
(27:51):
an extended period of media activity compared to other meteor showers,
which are usually over in just a matter of days. Now,
due to the gravitational perturbations planets, especially Jupiter, the Tourreds
have been spread out over time, allowing separate segments labeled
the Northern Toureds and Southern Torereads to be observable at
different times in different hemispheres. The Southern Tourreds are active
(28:13):
from around September tenth to November twentieth, while the Northern
Tourreds are active from October the twentieth to December tenth.
The third medior shower this month is the Orionids, which
peak on October the twentieth. They're caused by debris from
the Comet Halley, which also causes the Etta Accuridz media
shower in May. Commet Halley takes seventy six years to
(28:34):
complete each orbit around the Sun. It'll next become visible
near Earth in twenty sixty one. The Orionids are equally
spectacular in both northern and southern Hemisphere skies, with up
to twenty meteors an hour radiating out from the constellation Orion.
The best time to see the Orionids is just after
midnight and ripe before dusk. This is Spacetime and that's
(29:13):
the show for now. Spacetime is available every Monday, Wednesday
and Friday through Apple Podcasts, iTunes, Stitcher, Google podcast, pocker Casts, Spotify, Acast,
Amazon Music, Bites, dot Com, SoundCloud, YouTube, your favorite podcast
download provider, and from space Time with Stuart Gary dot com.
(29:34):
Space Time's also broadcast through the National Science Foundation, on
Science Own Radio and on both iHeartRadio and tune In Radio.
And you can help to support our show by visiting
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or by becoming a Spacetime Patron, which gives you access
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(29:55):
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