April 26, 2021 • 11 mins
On this day in 1986, a chemical explosion in a nuclear reactor at the Chernobyl nuclear power plant in Soviet Ukraine triggered one of the worst nuclear disasters ever. / On this day in 1920, astronomers Harlow Shapley and Heber Curtis presented their opposing points about the scale of the universe in an event sometimes called “The Great Debate.”
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Episode Transcript
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Speaker 1 (00:00):
Hey, everyone. Technically you're getting two days in history today
because we're running two episodes from the History Vault. I
hope you enjoy. Hey, guys, welcome to this Day in
History class, where we bring you a new tidbit from
history every day. The day was April nine. At the
(00:29):
Chernobyl Nuclear power Station and Soviet Ukraine, a chemical explosion
cost an enormous fire. Large quantities of radioactive material were
released into the atmosphere for nearly two weeks because of
the accident. Even though people in the nearby area were evacuated,
the wind spread the radiation, which contaminated land and caused
(00:52):
thousands of people to get radiation related illnesses. The Chernobyl
Power Station was in the town of Pripyat to us
northwest of the city of Chernobyl. The station was built
in the late nineteen seventies. It had four reactors, or
devices where nuclear fission is initiated and controlled in a
self sustaining chain reaction to create energy or radiation. Each
(01:17):
of the reactors could produce one thousand megawatts of electric power.
On the evening of April six, engineers began a test
on reactor Unit four. They wanted to figure out whether
the reactors turbine could run emergency water pumps during a
power loss, but the test and reactor were not designed will.
(01:40):
The engineers shut down the reactors, power regulating system and
emergency safety systems. Then they let the reactor run at
a low power and removed most of the control rods
from its core. Control rods maintained the fission rate in
a nuclear reactor. The reactor's output went up to two
hundred megawats, and at one am on April, the engineers
(02:04):
shut down the turbine engine to see if it's inertial
spinning would power the reactor's water pumps. It did not
because there was no cooling water. The reactor's power levels surged,
so the engineers put all the control rods back into
the reactor at once. That was supposed to prevent a meltdown.
(02:25):
The problem was the control rods had graphite tips. Those
graphite tips made the chain reaction in the court go
out of control and steam building up, and the reactor
blasted the steel and concrete lid off of it. Radioactive
debris went flying everywhere, and there was a partial meltdown
in the reactor core. Another explosion went off seconds later,
(02:48):
and the fire went off at reactor number three. Because
engineers had shut down emergency systems, safeties were not triggered,
though this was not a violation of regulations. The explosion
released four hundred times more radiation than the atomic bomb
the US dropped on Hiroshima. About thirty one people died
(03:09):
in the first few months after the explosion from the blast,
acute radiation, sickness, and cardiac arrest. Firefighters arrived minutes after
the fire started, but they were not wearing any gear
that would protect them from the radiation, and many of
them soon died from exposure. At five in the morning.
The next day, reactor three was shut down. The day
(03:32):
after that, reactors one and two were shut down. The
fire was put out with sand, lead and nitrogen, which
took about two weeks, But the accident had released extremely
dangerous levels of radioactive substances like I had died went
thirty one, plutonium and caesium one thirty seven. The plumes
(03:52):
of radioactive material released into the air were carried for
miles by currents of air lethal rain fail throughout Ukraine, Russia, Belarus,
Scandinavia and other parts of Europe. Many more people were
exposed to high doses of radiation. On the twenty seventh
of April, the Soviet government began evacuating crapyots tens of
(04:16):
thousands of residents. At the time, evacuates did not know
how serious the accident had been. At first, the Soviet
Union tried to keep the accident a secret, not announcing
the scale of the disaster. But a few days after
the explosion, Swedish officials realized that high radiation levels in
Europe were the result of a nuclear accident in the
(04:38):
Soviet Union. So in April, the Soviet Union announced that
there was an accident at Chernobyl. In May, hundreds of
thousands of people called liquidators were sent to Chernobyl to
help clean up. They worked in short shifts as they
did not have adequate protective gear. Over several months, a
(04:58):
huge steel and I meant sarcophagus was built to encase
reactor for and prevent the further spread of radiation. Still,
thousands of people remained in contaminated areas. People got sick
from the radiation, which increased the incidence of thyroid cancer.
Animals and forests were also affected. The Chernobyl power station
(05:22):
wasn't decommissioned until two thousand. In two thousand and sixteen,
a new confinement was placed over the old sarcophagus, which
had been deemed unsound. Today there is a Chernobyl exclusion
zone that's about one thousand square miles where people cannot
live in. Agriculture is not allowed, but there are animals
(05:42):
like wolves and bison living at the site. There are
plans for a solar power plant to be constructed at
the site, and people can visit the abandoned territory as tourists,
but the radio activity is still affecting people and likely
will for decades. For example, cows of miles away from
the site still produce milk with high levels of radiation.
(06:05):
The number of deaths caused by the radioactivity is controversial,
as the long term health effects of radiation are hard
to pinpoint and statistics can be unreliable. Many fears of
radiation induced health issues are unsubstantiated, but estimates of the
death toll have ranged from a few thousand to an
improbable million. I'm Eve jeffco and hopefully you know a
(06:31):
little more about history today than you did yesterday. If
there's something that I missed in an episode, you can
share it with everybody else on Twitter, Instagram or Facebook
at T d I h C podcast. We'll see you
here in the same place tomorrow. Hello everyone, I'm Eaves
(06:55):
and you're listening to this day history class of podcasts
that brings you a different moment in history every single day.
And before we start the show, I just wanted to
say that I know a lot of us are having
a really hard time now and we're in really different
situations than we're used to. But I do hope that
this podcast provides you with some sort of enlightenment or
(07:16):
a moment in your day that can help you carry
on and just operates as a reminder that time does
go on. The day was April nineteen. Astronomer Is Harlow
(07:40):
Shapley and Hayber Curtis presented their opposing points about the
scale of the universe in an event sometimes called the
Great Debate. Hayber Curtis found his interest in astronomy in
the eighteen nineties. He studied at the University of Virginia
on a Vanderbilt fellowship and got his doctorate there In
nineteen o two. Lick Observatory in California hired him and
(08:03):
He stayed at Lake for the next eighteen years. During
his time there, nebula were one of the subjects that
he was invested in. At the time, the word nebula
referred to any celestial object that appeared fuzzy through a telescope.
Through his work, Curtis began to support the island universe theory.
He was convinced that certain nebulae were island universes comparable
(08:25):
to our own galaxy. In nineteen eighteen, he published a
study of seven hundred and sixty two nebulae that he
had photographed with the Crossley reflector, but many other astronomers
were more skeptical of the theory. Harlow Shapley got his
doctorate in astronomy from Princeton University in nineteen thirteen. The
next year, he went to Mount Wilson Observatory in California.
(08:48):
There he studied the distribution of globular clusters in the
Milky Way. Through his observations, Shapily determined that our solar
system is not at the center of the galaxy. At
this point, it was widely believed that the Sun was
at the center of the galaxy, but Shapily concluded that
the Sun was around fifty thousand light years away from
the center. He also concluded that the galaxy was around
(09:12):
three hundred thousand light years in diameter and thirty thousand
light years thick. That meant that the galaxy was much
larger than previously thought. These numbers were later revised, but
his contributions provided a more realistic estimate for the size
of the galaxy. The nature of spiral nebulee was also
a subject of debate at the time. Shapley believed that
(09:35):
our galaxy is enormous and that spiral nebulea were part
of it, while Curtis did not buy into Shapley's size
for the Milky Way. However, Curtis maintained his belief that
spiral nebule were other galaxies comparable to the Milky Way.
Astronomer Adrian von Maanen's research on spiral nebulee at Mount
Wilson gave Shapley even more fuel to doubt the validity
(09:57):
of the island universe theory. These differences and thought led
to the so called Great Debate of April nineteen twenty.
Shapley and Curtis presented their positions at a meeting of
the National Academy of Sciences in Washington. D. C. Shapley
argued his findings on the large dimensions of the galaxy,
saying that if the spiral nebulae were as large as
(10:19):
our galaxy, they would have to be inconceivably large distances away.
He thought that the spiral nebulae were clusters made up
mostly of gas. Curtis, on the other hand, noted the
great distances to the spiral nebulee, arguing that all of
them could not be in our small Milky Way. No
clear winner emerged in the aftermath of the discussion, but
(10:42):
Shapily turned out to be right about the enormity of
the Milky Way and the Sun not being at its center,
and Curtis was right about the spiral nebulee being outside
our galaxy. In ninety four, astronomer Edwin Hubbell announced that
the spiral nebula Andromeda was actually a galaxy. Modern estimates
put the number of galaxies in the universe at two trillion.
(11:07):
I'm Eve Jeff Cote, and hopefully you know a little
more about history today than you did yesterday, And if
you'd like to send us any suggestions or comments, you
can hit us up on social media where at t
d i h C Podcast. You can also send us
an email at this Day at i heeart media dot com.
Thanks again for listening to the show and we'll see
(11:28):
you tomorrow. For more podcasts from I Heart Radio, visit
the iHeart Radio app, Apple Podcasts, or wherever you listen
to your favorite shows.
Hey, everyone. Technically you're getting two days in history today
because we're running two episodes from the History Vault. I
hope you enjoy. Hey, guys, welcome to this Day in
History class, where we bring you a new tidbit from
history every day. The day was April nine. At the
(00:29):
Chernobyl Nuclear power Station and Soviet Ukraine, a chemical explosion
cost an enormous fire. Large quantities of radioactive material were
released into the atmosphere for nearly two weeks because of
the accident. Even though people in the nearby area were evacuated,
the wind spread the radiation, which contaminated land and caused
(00:52):
thousands of people to get radiation related illnesses. The Chernobyl
Power Station was in the town of Pripyat to us
northwest of the city of Chernobyl. The station was built
in the late nineteen seventies. It had four reactors, or
devices where nuclear fission is initiated and controlled in a
self sustaining chain reaction to create energy or radiation. Each
(01:17):
of the reactors could produce one thousand megawatts of electric power.
On the evening of April six, engineers began a test
on reactor Unit four. They wanted to figure out whether
the reactors turbine could run emergency water pumps during a
power loss, but the test and reactor were not designed will.
(01:40):
The engineers shut down the reactors, power regulating system and
emergency safety systems. Then they let the reactor run at
a low power and removed most of the control rods
from its core. Control rods maintained the fission rate in
a nuclear reactor. The reactor's output went up to two
hundred megawats, and at one am on April, the engineers
(02:04):
shut down the turbine engine to see if it's inertial
spinning would power the reactor's water pumps. It did not
because there was no cooling water. The reactor's power levels surged,
so the engineers put all the control rods back into
the reactor at once. That was supposed to prevent a meltdown.
(02:25):
The problem was the control rods had graphite tips. Those
graphite tips made the chain reaction in the court go
out of control and steam building up, and the reactor
blasted the steel and concrete lid off of it. Radioactive
debris went flying everywhere, and there was a partial meltdown
in the reactor core. Another explosion went off seconds later,
(02:48):
and the fire went off at reactor number three. Because
engineers had shut down emergency systems, safeties were not triggered,
though this was not a violation of regulations. The explosion
released four hundred times more radiation than the atomic bomb
the US dropped on Hiroshima. About thirty one people died
(03:09):
in the first few months after the explosion from the blast,
acute radiation, sickness, and cardiac arrest. Firefighters arrived minutes after
the fire started, but they were not wearing any gear
that would protect them from the radiation, and many of
them soon died from exposure. At five in the morning.
The next day, reactor three was shut down. The day
(03:32):
after that, reactors one and two were shut down. The
fire was put out with sand, lead and nitrogen, which
took about two weeks, But the accident had released extremely
dangerous levels of radioactive substances like I had died went
thirty one, plutonium and caesium one thirty seven. The plumes
(03:52):
of radioactive material released into the air were carried for
miles by currents of air lethal rain fail throughout Ukraine, Russia, Belarus,
Scandinavia and other parts of Europe. Many more people were
exposed to high doses of radiation. On the twenty seventh
of April, the Soviet government began evacuating crapyots tens of
(04:16):
thousands of residents. At the time, evacuates did not know
how serious the accident had been. At first, the Soviet
Union tried to keep the accident a secret, not announcing
the scale of the disaster. But a few days after
the explosion, Swedish officials realized that high radiation levels in
Europe were the result of a nuclear accident in the
(04:38):
Soviet Union. So in April, the Soviet Union announced that
there was an accident at Chernobyl. In May, hundreds of
thousands of people called liquidators were sent to Chernobyl to
help clean up. They worked in short shifts as they
did not have adequate protective gear. Over several months, a
(04:58):
huge steel and I meant sarcophagus was built to encase
reactor for and prevent the further spread of radiation. Still,
thousands of people remained in contaminated areas. People got sick
from the radiation, which increased the incidence of thyroid cancer.
Animals and forests were also affected. The Chernobyl power station
(05:22):
wasn't decommissioned until two thousand. In two thousand and sixteen,
a new confinement was placed over the old sarcophagus, which
had been deemed unsound. Today there is a Chernobyl exclusion
zone that's about one thousand square miles where people cannot
live in. Agriculture is not allowed, but there are animals
(05:42):
like wolves and bison living at the site. There are
plans for a solar power plant to be constructed at
the site, and people can visit the abandoned territory as tourists,
but the radio activity is still affecting people and likely
will for decades. For example, cows of miles away from
the site still produce milk with high levels of radiation.
(06:05):
The number of deaths caused by the radioactivity is controversial,
as the long term health effects of radiation are hard
to pinpoint and statistics can be unreliable. Many fears of
radiation induced health issues are unsubstantiated, but estimates of the
death toll have ranged from a few thousand to an
improbable million. I'm Eve jeffco and hopefully you know a
(06:31):
little more about history today than you did yesterday. If
there's something that I missed in an episode, you can
share it with everybody else on Twitter, Instagram or Facebook
at T d I h C podcast. We'll see you
here in the same place tomorrow. Hello everyone, I'm Eaves
(06:55):
and you're listening to this day history class of podcasts
that brings you a different moment in history every single day.
And before we start the show, I just wanted to
say that I know a lot of us are having
a really hard time now and we're in really different
situations than we're used to. But I do hope that
this podcast provides you with some sort of enlightenment or
(07:16):
a moment in your day that can help you carry
on and just operates as a reminder that time does
go on. The day was April nineteen. Astronomer Is Harlow
(07:40):
Shapley and Hayber Curtis presented their opposing points about the
scale of the universe in an event sometimes called the
Great Debate. Hayber Curtis found his interest in astronomy in
the eighteen nineties. He studied at the University of Virginia
on a Vanderbilt fellowship and got his doctorate there In
nineteen o two. Lick Observatory in California hired him and
(08:03):
He stayed at Lake for the next eighteen years. During
his time there, nebula were one of the subjects that
he was invested in. At the time, the word nebula
referred to any celestial object that appeared fuzzy through a telescope.
Through his work, Curtis began to support the island universe theory.
He was convinced that certain nebulae were island universes comparable
(08:25):
to our own galaxy. In nineteen eighteen, he published a
study of seven hundred and sixty two nebulae that he
had photographed with the Crossley reflector, but many other astronomers
were more skeptical of the theory. Harlow Shapley got his
doctorate in astronomy from Princeton University in nineteen thirteen. The
next year, he went to Mount Wilson Observatory in California.
(08:48):
There he studied the distribution of globular clusters in the
Milky Way. Through his observations, Shapily determined that our solar
system is not at the center of the galaxy. At
this point, it was widely believed that the Sun was
at the center of the galaxy, but Shapily concluded that
the Sun was around fifty thousand light years away from
the center. He also concluded that the galaxy was around
(09:12):
three hundred thousand light years in diameter and thirty thousand
light years thick. That meant that the galaxy was much
larger than previously thought. These numbers were later revised, but
his contributions provided a more realistic estimate for the size
of the galaxy. The nature of spiral nebulee was also
a subject of debate at the time. Shapley believed that
(09:35):
our galaxy is enormous and that spiral nebulea were part
of it, while Curtis did not buy into Shapley's size
for the Milky Way. However, Curtis maintained his belief that
spiral nebule were other galaxies comparable to the Milky Way.
Astronomer Adrian von Maanen's research on spiral nebulee at Mount
Wilson gave Shapley even more fuel to doubt the validity
(09:57):
of the island universe theory. These differences and thought led
to the so called Great Debate of April nineteen twenty.
Shapley and Curtis presented their positions at a meeting of
the National Academy of Sciences in Washington. D. C. Shapley
argued his findings on the large dimensions of the galaxy,
saying that if the spiral nebulae were as large as
(10:19):
our galaxy, they would have to be inconceivably large distances away.
He thought that the spiral nebulae were clusters made up
mostly of gas. Curtis, on the other hand, noted the
great distances to the spiral nebulee, arguing that all of
them could not be in our small Milky Way. No
clear winner emerged in the aftermath of the discussion, but
(10:42):
Shapily turned out to be right about the enormity of
the Milky Way and the Sun not being at its center,
and Curtis was right about the spiral nebulee being outside
our galaxy. In ninety four, astronomer Edwin Hubbell announced that
the spiral nebula Andromeda was actually a galaxy. Modern estimates
put the number of galaxies in the universe at two trillion.
(11:07):
I'm Eve Jeff Cote, and hopefully you know a little
more about history today than you did yesterday, And if
you'd like to send us any suggestions or comments, you
can hit us up on social media where at t
d i h C Podcast. You can also send us
an email at this Day at i heeart media dot com.
Thanks again for listening to the show and we'll see
(11:28):
you tomorrow. For more podcasts from I Heart Radio, visit
the iHeart Radio app, Apple Podcasts, or wherever you listen
to your favorite shows.
This Day in History Class News
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