APOD: 2024 October 20 Б Dark Matter in a Simulated Universe
20.10.2024

Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters...

Magnetar
27.05.1998

What do you call a neutron star with a super-strong magnetic field? You guessed it ... a Magnetar. Imagine a star with more mass than the sun, the density of a neutron, and a magnetic field about a thousand trillion (a one followed by 15 zeroes) times stronger than Earth's.

Flying Past Pluto
6.10.2015

What would it look like to fly past Pluto? The robotic New Horizons spacecraft did just this in late July and continues to return stunning pictures of the dwarf planet. Some well-chosen flyby images have now been digitally sequenced to create the featured video.

Leonid Meteors Streak
23.11.2004

The 2004 Leonids meteor shower had its ups and downs. Although average rates were significantly less than many previous years, as expected, at least two unexpected "mini-outbursts" of several bright meteors over a few minutes were reported.

Sun 360: STEREO Captures Views of the Entire Sun
7.02.2011

For the first time, the entire Sun is being imaged all at once. This has become possible because the two STEREO satellites orbiting and monitoring the Sun are now on opposite sides of the Sun.

APOD: 2023 June 18 Б Saturns Northern Hexagon
18.06.2023

Why would clouds form a hexagon on Saturn? Nobody is sure. Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System.

APOD: 2023 July 3 Б Venus in Ultraviolet from Akatsuki
3.07.2023

Why is Venus so different from Earth? To help find out, Japan launched the robotic Akatsuki spacecraft which entered orbit around Venus late in 2015 after an unplanned five-year adventure around the inner Solar System.

The W in Cassiopeia
18.03.2016

A familiar, zigzag, W pattern in northern constellation Cassiopeia is traced by five bright stars in this colorful and broad mosaic. Stretching about 15 degrees across rich starfields, the celestial scene includes dark clouds, bright nebulae, and star clusters along the Milky Way. In yellow-orange hues Cassiopeia's alpha star Shedar is a standout though.

Julius Caesar and Leap Days
29.02.2020

In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long.

Phi Persei: Double Star
2.10.1999

It's clear who is the biggest star in this binary system. Based on recent results, this artist's vision of the double star Phi Persei, 720 light years away, shows a bright, rapidly rotating massive star surrounded by a disk of gas. A small companion star orbits 100 million miles away.