StarDate

Meteor’ology

Meteorology is the study of Earth’s atmosphere and its weather and climate. Despite the name, it has nothing to do with meteors – at least not directly. But more broadly,

Ancient Meteorites

The oldest objects on Earth didn’t come from our home planet. They were born in space more than four-and-a-half billion years ago. They fell to Earth as the most common t

Getting the Scale

The solar system is big. Really big. It’s almost three billion miles from the Sun to Neptune, the most distant major planet. It’s more than three billion miles to Pluto.

Missing Sibling

A meteorite found in the Sahara Desert could be a fragment of a destroyed sibling of Earth. The small planet might have been blasted to rubble when the solar system was y

Moon and Antares

Antares, the bright star at the heart of Scorpius, huddles quite close to the Moon early this evening. They set not long after the sky gets dark, so there’s not a lot of

New Crater

The surface of the Moon seems eternal. There’s no air or water to reshape it, and no plate tectonics to jiggle things around. But the Moon does change – sometimes in a hu

Vesta

The second-largest asteroid in the solar system is a puzzler. Most studies say it has the same layers as a planet, but that it’s not massive enough to pull itself into a

Messier 10

The stars in a binary system can be quite intimate. One star can pull gas off the surface of its companion, for example. And in extreme cases, the stars can merge to form

Double Cluster

A pair of big, young star clusters is one of the skywatching highlights of autumn evenings. Each cluster contains thousands of stars. And hundreds of those stars are espe

Caroline’s Rose

Cassiopeia is an easy constellation to pick out. The stars of the queen form a prominent letter M or W, which is visible even through moderate light pollution. And under

Quiet Monster

A quiet monster lurks in the heart of M31, the Andromeda Galaxy. Known as M31-star, it’s a black hole a hundred million times the mass of the Sun, and 25 times heavier th

Andromeda Galaxy

Two-and-a-half million years ago, Earth was going through some big changes. It was the start of the Pleistocene epoch – a period of major ice ages. And the ancestors of m

Moon and Regulus

The Moon has had a busy social calendar this week. It’s had meet-and-greets with the twins of Gemini and the planets Mars and Jupiter. And it has one more engagement tomo

Moon and Jupiter

For skywatchers across the eastern United States, the planet Jupiter will vanish early tomorrow – hidden behind the crescent Moon. The rest of the country will see an imp

Moon and Mars

To borrow from “Alice in Wonderland,” the case for life on Mars keeps getting curiouser and curiouser. Two rovers have discovered organic compounds there – the chemical b

Moon and Companions

The Moon will run a gauntlet of bright stars and planets the next few mornings, from the twins of Gemini to the heart of the lion. The twins are up first. Pollux and Cast

Saturn Opposition III

Saturn is a “superior” planet. Among other things, it’s the second-largest and second-heaviest planet in the solar system. Technically, though, what makes it “superior” i

Saturn Opposition II

This isn’t a sound effect from a sci-fi movie. Instead, it’s the “voice” of the auroras on the planet Saturn – radio waves that have been shifted to wavelengths we can he

Saturn at Opposition

Saturn puts in its best appearance of the year over the next few nights. On Sunday, it’ll reach opposition – it will line up opposite the Sun. It’s closest to Earth at op

Kaus Australis

To modern eyes, the stars of Sagittarius form the outline of a teapot. But in Greek mythology, the constellation was far more extensive. It represented a centaur – half-m