Orion Star Colours
29.08.1998

What determines a star's colour? Its temperature. Red stars are cool, around 3,000 kelvins (K), while blue stars are hotter and can have temperatures over 30,000 K. Our own lovely yellow Sun's temperature is a comforting 6,000 K.

Shadows Across Jupiter
15.02.2013

Two dark shadows loom across the banded and mottled cloud tops of Jupiter in this sharp telescopic view. In fact, captured on January 3rd, about a month after the ruling gas giant appeared at opposition in planet Earth's sky, the scene includes the shadow casters.

Spica, Mars, and Eclipsed Moon
16.04.2014

A beautiful, reddened Moon slid through dark skies on April 15, completely immersed in Earth's shadow for well over an hour. It was the year's first total lunar eclipse and was widely enjoyed over the planet's Western Hemisphere.

Saturn at the Lunar Limb
22.02.2002

Gliding through the sky on Wednesday evening, February 20th, a first quarter Moon seemed to run over bright planet Saturn as viewed from much of North America. In this sharp sequence of telescopic digital...

The Lagoon Nebula in Gas, Dust, and Stars
22.07.2009

Stars are battling gas and dust in the Lagoon Nebula but the photographers are winning. Also known as M8, this photogenic nebula is visible even without binoculars towards the constellation of Sagittarius. The energetic processes of star formation create not only the colors but the chaos.

In the Center of NGC 6559
29.06.2004

Bright gas and dark dust permeate the space between stars in the center of a nebula known as NGC 6559. The gas, primarily hydrogen, is responsible for the diffuse red glow of the emission nebula.

Pick a Galaxy Any Galaxy
17.01.2002

Pick a galaxy, any galaxy. In the top panel you can choose from a myriad of distant galaxies revealed in a deep Hubble Space Telescope image of a narrow slice of the cosmos toward the constellation Hercules.

APOD: 2026 June 29 Б M82: Galaxy with a Supergalactic Wind
29.06.2026

Why is the Cigar Galaxy billowing red smoke? M82, as this starburst galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas and dust, however.

The Sun Today
18.05.1996

Our Sun shows a different face every day. The above picture was taken on May 15, but a similar picture of the Sun actually taken today can be found here. The above picture was taken in red light and so is shown in red.

Light from the Heart Nebula
3.10.2006

What powers the Heart Nebula? The large emission nebula dubbed IC 1805 looks, in whole, like a human heart. The nebula glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center.