The Andromeda Galaxy, like all spirals, shows a population of older, redder stars near its center (lower right) and younger, bluer stars in its surrounding spiral arms. Walter Baade discovered the different populations through observations made during World War II. NOAO/AURA/NSF If you've been watching...

After the Sun sets over the Atacama Desert’s Valley of the Moon, the 19,400-foot volcano Licancabur catches the last rays of sunlight. Richard Talcott I recently returned from a 9-day trip to Chile — one of more than 30 participants in a tour sponsored by Astronomy magazine and organized...

Early morning steam rises from numerous geysers and fumaroles at El Tatio — the world’s highest-altitude geyser field. Evelyn Talcott I've just returned from a 9-day trip to Chile & one of more than 30 participants in a tour sponsored by Astronomy magazine and organized by MWT Associates...

Saturn's rings glint brightly thanks to the "opposition effect" in this June 12 image, taken by the Cassini spacecraft. NASA/JPL/SSI While I was out walking Wednesday evening, brilliant Jupiter stood slightly above the gibbous Moon. With the Moon waxing toward its full phase this weekend...

The first photo ever taken from the surface of Mars showed lots of rocks and sand — and the footpad of the Viking 1 lander. NASA/JPL Virtually everyone who reads this blog knows what happened on this date in history. But I'm not going to spend much time talking about Neil Armstrong's and...

Several dark spots mar Jupiter’s atmosphere after Comet Shoemaker-Levy 9 smashed into it between July 16 and 22, 1994. NASA/Hubble Space Telescope Science Team Where were you 13 years ago? If you're like me, you were eagerly anticipating a once-in-a-lifetime event — with no clue as to...

That bright point of light you see hanging in the western sky after sunset is none other than Venus. Aim your telescope at it, and you'll find it's more than a point. The "evening star" currently displays a disk some 25" across and just under half-lit. Sure, Venus appears bright...

After a weeklong stretch of off-and-on clouds, Tuesday evening dawned clear in Wisconsin. There, gleaming in the west as it has for the past several months, brilliant Venus dominated the sky. But Venus had added allure this evening: A new spacecraft was skimming just above its cloud tops. No, I couldn't...

Head outside this evening, and you can't help but notice a Full Moon rising in the southeast. Nothing unusual about that — Full Moons occur, on average, every 29.5306 days. But if you look at your calendar for May, you'll see the previous Full Moon fell May 2, making tonight's the second...

Saturn’s rings tell a story regardless of their color. This image, created from Cassini spacecraft observations of stellar occultations, reveals ring particles clump together far more than astronomers previously thought. NASA/JPL/University of Colorado Most of the time, Saturn's splendor appears...