APOD: 2026 April 15 Б The ISS Transits the Moon
15.04.2026

Nope, that is not an alien spaceship landing on the Moon! This is an image of the International Space Station (ISS) as it begins to transit in front of the Moon. The ISS is in low-Earth orbit (LEO) where it wizzes around the Earth every 90 minutes.

Unusual Flashes Toward Globular Cluster M22
3.07.2001

What is causing the unusual flashes behind globular cluster M22? This teaming ball of stars is the brightest globular cluster visible in Earth's northern hemisphere. M22, shown in full in the inset, spans about 50 light years away and lies 8500 light-years toward the constellation of Sagittarius.

The Making of the Rotten Egg Nebula
3.09.2001

Fast expanding gas clouds mark the end for a central star in the Rotten Egg Nebula. The once-normal star has run out of nuclear fuel, causing the central regions to contract into a white dwarf. Some of the liberated energy causes the outer envelope of the star to expand.

Galactic Center Flicker Indicates Black Hole
10.09.2001

Why would the center of our Galaxy flicker? Many astronomers believe the only credible answer involves a black hole. During observations of Sagittarius A* with the orbiting Chandra X-ray Observatory, the bright X-ray source at the very center of our Milky Way brightened dramatically for a few minutes.

1006 AD: Supernova in the Sky
28.03.2003

A new star, likely the brightest supernova in recorded human history, appeared in planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion is still visible to modern astronomers, but what did the supernova look like in 1006?

M106 in Canes Venatici
17.04.2003

Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial nebula was discovered in 1781 by the metric French astronomer Pierre Mechain and later added to the catalog of his friend and colleague Charles Messier as M106.

The Moon Maiden
19.06.2003

Along the northwestern reaches of the lunar near side, the Sinus Iridium or Bay of Rainbows appropriately lies at the edge of the Moon's smooth, dark Sea of Rains (Mare Imbrium). In this...

Voyage of an Antarctic Iceberg
23.02.2005

What if part of New York broke off and slammed into New Jersey? Both being anchored land masses, that is unlikely to happen, but an event of that size scale did occur off the Antarctic coast over the last three months.

Three Month Composite of Comet Holmes
5.02.2008

How has Comet Holmes changed? Since brightening unexpectedly by nearly one million fold in late October, the last three months have found the coma of Comet 17P/Holmes both expanding and fading. This spectacular composite image shows how the coma and tail of Comet Holmes have changed.

Planetary Nebula NGC 2818
22.01.2009

NGC 2818 is a beautiful planetary nebula, the gaseous shroud of a dying sun-like star. It could well offer a glimpse of the future that awaits our own Sun after spending another 5 billion years or so steadily using up hydrogen at its core, and then finally helium, as fuel for nuclear fusion.