Ios Surface: Under Construction
4.08.2013

Like the downtown area of your favorite city and any self-respecting web site ... Io's surface is constantly under construction. This moon of Jupiter holds the distinction of being the Solar System's most volcanically active body -- its bizarre looking surface continuously formed and reformed by lava flows.

Equinox on a Spinning Earth
19.03.2014

When does the line between day and night become vertical? Tomorrow. Tomorrow is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles.

HCG 87: A Small Group of Galaxies
9.08.2015

Sometimes galaxies form groups. For example, our own Milky Way Galaxy is part of the Local Group of Galaxies. Small, compact groups, like Hickson Compact Group 87 (HCG 87) shown above, are interesting partly because they slowly self-destruct.

IC 5067 in the Pelican Nebula
26.05.2016

The prominent ridge of emission featured in this sharp, colorful skyscape is cataloged as IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years following the curve of the cosmic pelican's head and neck.

Big Dipper Above and Below Chilean Volcanoes
9.05.2017

Do you see it? This common question frequently precedes the rediscovery of one of the most commonly recognized configurations of stars on the northern sky: the Big Dipper. This grouping of stars is one of the few things that has likely been seen, and will be seen, by every generation.

M95: Spiral Galaxy with an Inner Ring
29.05.2019

Why do some spiral galaxies have a ring around the center? First and foremost, M95 is one of the closer examples of a big and beautiful barred spiral galaxy. Visible in the featured combination...

Sharpless 308: The Dolphin Nebula
2.03.2020

Blown by fast winds from a hot, massive star, this cosmic bubble is much larger than the dolphin it appears to be. Cataloged as Sharpless 2-308 it lies some 5,200 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a Full Moon.

Behind Betelgeuse
11.05.2020

What's behind Betelgeuse? One of the brighter and more unusual stars in the sky, the red supergiant star Betelgeuse can be found in the direction of famous constellation Orion. Betelgeuse, however, is actually...

APOD: 2023 March 1 Б The Flaming Star Nebula
1.03.2023

Is star AE Aurigae on fire? No. Even though AE Aurigae is named the Flaming Star and the surrounding nebula IC 405 is named the Flaming Star Nebula, and even though the nebula appears to some like a swirling flame, there is no fire.

APOD: 2023 July 11 Б Sunspots on an Active Sun
11.07.2023

Why is our Sun so active now? No one is sure. An increase in surface activity was expected because our Sun is approaching solar maximum in 2025. However, last month our Sun sprouted more sunspots than in any month during the entire previous 11-year solar cycle -- and even dating back to 2002.