M13: The Great Globular Cluster in Hercules
20.05.2021

In 1716, English astronomer Edmond Halley noted, "This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent." Of course...

Colorful Airglow Bands Surround Milky Way
13.03.2022

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere.

M13: The Great Globular Cluster in Hercules
15.11.2007

M13 is modestly recognized as the Great Globular Cluster in Hercules. A system of stars numbering in the hundreds of thousands, it is one of the brightest globular star clusters in the northern sky.

Night of the Long Leonid
22.11.2012

A cosmic grain of sand left the long and colorful trail across this all-sky view. Its grazing impact with planet Earth's atmosphere began at 71 kilometers per second. With the Milky Way stretching...

Close Comet and the Milky Way
25.03.2016

Comet 252P/Linear's lovely greenish coma is easy to spot in this expansive southern skyscape. Visible to the naked eye from the dark site near Flinders, Victoria, Australia, the comet appears tailless. Still, its surprisingly bright coma spans about 1 degree, posed here below the nebulae, stars, and dark rifts of the Milky Way.

Mars in Taurus
4.03.2021

You can spot Mars in the evening sky tonight. Now home to the Perseverance rover, the Red Planet is presently wandering through the constellation Taurus, close on the sky to the Seven Sisters or Pleiades star cluster.

NGC 4565: Galaxy on Edge
17.05.2021

Is our Milky Way Galaxy this thin? Magnificent spiral galaxy NGC 4565 is viewed edge-on from planet Earth. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices.

APOD: 2026 August 20 Б The Elephant s Trunk in Cepheus
20.08.2026

Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission region and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, this cosmic elephant's trunk is over 20 light-years long.

Clouds and Sand on the Horizon of Mars
17.10.2006

If you could stand on Mars -- what might you see? Like the robotic Opportunity rover rolling across the red planet, you might well see vast plains of red sand, an orange tinted sky, and wispy light clouds.

Baryon Acoustic Oscillations from SDSS III
20.01.2014

How large do things appear when far away? When peering across the universe, the answer can actually tell us about its average gravitational history and hence its composition. Toward this goal, the Baryon Oscillation...