When Black Holes Collide
19.10.2015

What happens when two black holes collide? This extreme scenario likely occurs in the centers of some merging galaxies and multiple star systems. The featured video shows a computer animation of the final stages of such a merger, while highlighting the gravitational lensing effects that would appear on a background starfield.

Magnetic Orion
26.02.2019

Can magnetism affect how stars form? Recent analysis of Orion data from the HAWC+ instrument on the airborne SOFIA observatory indicate that, at times, it can. HAWC+ is able to measure the polarization of far-infrared light which can reveal the alignment of dust grains by expansive ambient magnetic fields.

APOD: 2024 September 3 Б Quarter Moon and Sister Stars
2.09.2024

Nine days ago, two quite different sky icons were imaged rising together. Specifically, Earth's Moon shared the eastern sky with the sister stars of the Pleiades cluster, as viewed from Alberta, Canada. Astronomical...

Moons, Rings, and Unexpected Colors on Saturn
20.10.2008

Why would Saturn show such strange colors? The robotic Cassini spacecraft currently orbiting Saturn has beamed back images showing that the northern hemisphere our Solar System's most spectacularly ringed planet has changed noticeably since Cassini arrived in 2004, now sporting unusual and unexpected colors. No one is sure why.

Earth at Night
7.12.2012

This remarkably complete view of Earth at night is a composite of cloud-free, nighttime images. The images were collected during April and October 2012 by the Suomi-NPP satellite from polar orbit about 824 kilometers (512 miles) above the surface using its Visible Infrared Imaging Radiometer Suite (VIIRS).

Inside the Coma Cluster of Galaxies
28.02.2015

Almost every object in the above photograph is a galaxy. The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies. Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does.

Lunar Eclipse Perspectives
4.02.2020

Do we all see the same Moon? Yes, but we all see it differently. One difference is the apparent location of the Moon against background stars -- an effect known as parallax. We humans use the parallax between our eyes to judge depth.

Hot Gas and Dark Matter
4.04.1999

Is the gravity of the galaxies seen in this image high enough to contain the glowing hot gas? Superposed on an optical picture of a group of galaxies is an image taken in X-ray light.

APOD: 2025 July 1 Б Eye Sky a Dragon
30.06.2025

What do you see when you look into this sky? In the center, in the dark, do you see a night sky filled with stars? Do you see a sunset to the left? Clouds all around? Do you see the central band of our Milky Way Galaxy running down the middle?

Io: Moon Over Jupiter
20.04.2001

How big is the Jovian moon Io? The most volcanic body in the Solar System, Io (usually pronounced "EYE-oh") is 3,600 kilometers in diameter, about the size of planet Earth's single large natural satellite.