StarDate

No one has seen Comet Halley in decades. Even so, it’s reminding us of its presence about now. That’s because it’s responsible for the Eta Aquarid meteor shower. The shower is predicted to reach its peak tomorrow night, with top rates of about 40 or 50 meteors per hour.

A meteor shower occurs when Earth passes through the orbital path of a comet. As a comet nears the Sun, some of the ice at its surface vaporizes i...

The Moon and Mars are flirting with danger – they’re sneaking up on the Beehive star cluster, in the constellation Cancer. The cluster doesn’t have much of a “sting,” though – it’s about 600 light-years away.

The Beehive contains about a thousand stars, which are maybe 700 million years old – fairly young in astronomical terms. That means the Beehive maintains a mixture of stars of di...

The universe can be frustrating. Roughly two-thirds of everything in the universe appears to consist of dark energy. Despite decades of study, though, scientists haven’t been able to explain what dark energy is.

Astronomers discovered dark energy by studying a type of supernova – exploding stars. The supernovas brighten and fade in a predictable way. That allows astronomers to measure their distance and their motion awa...

The modern western calendar tells us that summer arrives in the northern hemisphere this year on June 20th – the summer solstice. It’s the longest day of the year, and the Sun stands farthest north for the year as well.

In ages past, many calendars had a less direct link to the solstices and equinoxes. The seasons began not on these dates, but about halfway between them. Such dates are known as “cross-quarter̶...

Telescope domes are designed to keep the telescopes inside safe and on-target. But just because they’re practical doesn’t mean they can’t be beautiful. That’s especially true of some built in the 1930s. They were influenced by the design style that was all the rage – known today as art deco.

The event that popularized art deco began 100 years ago this week – the International Exhibition of Decora...

Until about 30 years ago, Jupiter was the king of the planets – bigger and heavier than any other known planet. Today, it’s not even in the top 500. It’s still the giant of our own solar system – it’s more massive than all the other planets and moons combined. But hundreds of planets in other star systems outrank it.

The total number of confirmed exo-planets is up to about 6,000. They range from chunks...

Trillions of icy bodies mark the edge of the solar system. They form a shell that extends one or two light-years from the Sun in every direction. A passing star may sometimes give some of them a nudge toward the Sun. When they get here, they become comets – visitors from the icy deep.

That distant region is known as the Oort Cloud. It’s named for Dutch astronomer Jan Oort, who was born 125 years ago today. He proposed t...

Dark spots sometimes dot the surface of the Sun – magnetic storms that can last for days or weeks. But the storms on other stars can make those on the Sun look puny. They can be so monstrous that they can change the star’s brightness by quite a bit.

An example is one of the stars of Cor Caroli – the Heart of Charles. As seen by the eye alone, the star is the leading light of Canes Venatici, the hunting dogs. It...

The stars Kochab and Pherkad serve several roles. They’re part of the body of Ursa Minor, the little bear. They form the outer edge of the bowl of the Little Dipper. And they’re “guardians of the pole” – they circle around Polaris, the star that marks the north celestial pole.

Both stars are giants – they’ve puffed up at the end of the prime phase of life. Kochab is about 50 times the Sun&#...