StarDate

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 Castor will perch to the upper left of the Moon at dawn tomorrow. Pollux is the brighter of the two, and it’ll be closer to the Moon. On the following mornings, the Moon will slide past Mars, Jupiter, and Regulus.These encounters are...

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” is its location. It’s the sixth planet from the Sun, so its orbit is outside Earth’s orbit.Superior planets can line up opposite the Sun in our sky – a point known as opposition. And that’s what Saturn is doing now. It’ll reach...

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 hear. They were recorded by the Cassini spacecraft as it closed in on Saturn two decades ago.The radio waves are produced by the complex interplay between Saturn’s magnetic field and the solar wind – a steady flow of charged...

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 opposition, so it shines brightest. And it’s in view all night. It looks like a bright golden star. It’s low in the east at nightfall, and climbs high across the south later on.Saturn reaches opposition every 12 and a half months –...

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-man, half-horse – holding a bow and arrow. And the brightest star in the constellation plays a role in both of those pictures.Kaus Australis is at the lower right corner of the teapot. It also represents the southern end of the...

Galaxies aren’t good neighbors. They can stretch and pull the galaxies around them, rip them apart, and even gobble them up.A case in point is the Magellanic Clouds – the largest satellite galaxies of the Milky Way. The Large Magellanic Cloud is about 165,000 light-years away. It’s about a third as wide as the Milky Way, and perhaps one-tenth as massive. The small cloud is a little smaller and...

If you’re searching for life on another world, you don’t want to find life that’s hitchhiked from Earth. But preventing contamination isn’t easy.Over the past few decades, we’ve identified quite a few worlds in the outer solar system that could be habitable. These worlds are coated with frozen water. But they could have oceans of liquid water below the crust. Those oceans could supply the...

The Moon is full today. But it’s not just any old full Moon. It’s the best-known of them all: the Harvest Moon – the subject of books, music, and lots of fall festivals.In centuries past, the Harvest Moon was much more than a pop-culture event. It provided enough light for farmers to harvest their crops well into the night. And at high northern latitudes, it helped out for several nights in a...

Neptune has lost its vibrancy. The planet itself hasn’t changed – only our perception of it – the result of a bit of creative license exercised 37 years ago.Neptune is the Sun’s fourth-largest planet – four times the diameter of Earth. But it’s also the most-distant major planet – 30 times farther from the Sun than Earth is.Our only close look at Neptune came in August 1989, when Voyager 2 flew...

The largest moon of Neptune was an agent of chaos. It wasn’t born with Neptune itself. Instead, it was captured by the giant planet. As it spiraled in, it might have hit one of Neptune’s existing moons. And it scattered the others – knocking some of them out of orbit. Only one of them might have survived.There’s a lot of evidence of that idea. Triton is about the same size and composition as...