Three Tails of Comet NEOWISE
7.03.2021

What created the unusual red tail in Comet NEOWISE? Sodium. A spectacular sight back in the summer of 2020, Comet NEOWISE, at times, displayed something more than just a surprisingly striated white dust tail and a pleasingly patchy blue ion tail.

Explosions from White Dwarf Star RS Oph
21.08.2021

Spectacular explosions keep occurring in the binary star system named RS Ophiuchi. Every 20 years or so, the red giant star dumps enough hydrogen gas onto its companion white dwarf star to set off a brilliant thermonuclear explosion on the white dwarf's surface.

Sun Spot Hill
20.09.2021

Is this giant orange ball about to roll down that tree-lined hill? No, because the giant orange ball is actually the Sun. Our Solar System's central star was captured rising beyond a hill on Earth twelve days ago complete with a delightfully detailed foreground.

Pleiades: The Seven Sisters Star Cluster
23.11.2021

Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as large and clear as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city.

APOD: 2025 June 29 Б Dark Sand Cascades on Mars
28.06.2025

Are these trees growing on Mars? No. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The featured image was taken in 2008 April near the North Pole of Mars.

APOD: 2025 August 13 Б Trapezium: In the Heart of Orion
12.08.2025

What lies in the heart of Orion? Trapezium: four bright stars, that can be found near the center of this sharp cosmic portrait. Gathered within a region about 1.5 light-years in radius, these stars dominate the core of the dense Orion Nebula Star Cluster.

The Dumbbell Nebula in Hydrogen and Oxygen
12.01.2003

The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of "annoying" diffuse objects not to be confused with "interesting" comets.

Jovian Aurora
22.01.1998

These two recently released Hubble Space Telescope close-ups show the Northern and Southern lights ... on Jupiter. Like aurora on Earth, these Jovian aurora are caused by charged particles funneled into the atmosphere above the planet's North (right) and South poles by magnetic fields.

Solar System Portrait
13.02.2004

On another Valentine's Day (February 14, 1990), cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back to make this first ever family portrait of our Solar System. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane.

Asteroid 2004 FH Whizzes By
21.03.2004

Last week, a small asteroid approached unusually close to the Earth. Asteroid 2004 FH posed no danger, but became bright enough to see with binoculars. Passing only 7 Earth radii away, this asteroid pass was the closest yet that was previously predicted, although it was discovered only two days before.