Mizar Binary Star
19.02.1997

Mizar (sounds like "My Czar") is a binary star. In fact, most stars are binary stars. In a binary star system, each star of the pair follows an elliptical orbital path. Mutual gravity causes...

M57: The Ring Nebula
5.06.2013

Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. Its classic appearance is understood to be due to our own perspective, though. The recent mapping...

The X Ray Sky from eROSITA
23.06.2020

What if you could see X-rays? The night sky would seem a strange and unfamiliar place. X-rays are about 1,000 times more energetic than visible light photons and are produced by violent explosions and high temperature astronomical environments.

APOD: 2025 August 9 Б Interstellar Interloper 3I/ATLAS from Hubble
9.08.2025

Discovered on July 1 with the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) survey telescope in Rio Hurtado, Chile, 3I/ATLAS is so designated as the third known interstellar object to pass through our Solar System. It follows 1I/йOumuamua in 2017 and the comet 2I/Borisov in 2019.

The Brightest Spot on Ceres
11.12.2015

Dwarf planet Ceres is the largest object in the Solar System's main asteroid belt with a diameter of about 950 kilometers. Exploring Ceres from orbit since March, the Dawn spacecraft's camera...

The Milky Way s Black Hole
13.05.2022

There's a black hole at the center of the Milky Way. Stars are observed to orbit a very massive and compact object there known as Sgr A* (say "sadge-ay-star"). But this just released...

APOD: 2006 September 28- RCW 86: Historical Supernova Remnant
28.09.2006

In 185 AD, Chinese astronomers recorded the appearance of a new star in the Nanmen asterism - a part of the sky identified with Alpha and Beta Centauri on modern star charts. The new star was visible for months and is thought to be the earliest recorded supernova.

Active Region 1002 on an Unusually Quiet Sun
24.09.2008

Why has the Sun been so quiet recently? No one is sure. Our Sun has shown few active regions -- that house even fewer associated sunspots -- for over a year now, and such a period of relative calm is quite unusual.

High Energy Stereoscopic System II
27.07.2012

The largest of its kind, the High Energy Stereoscopic System (H.E.S.S.) II telescope stands in the foreground of this photo. Tilted horizontally it reflects the inverted landscape of the Namibian desert in a segmented mirror 24 meters wide and 32 meters tall, equal in area to two tennis courts.

Curiosity Rover at Rocknest on Mars
27.12.2012

What's in this smooth soil on Mars? In late October, NASA's robotic Curiosity rover stopped near a place dubbed Rocknest as it continues to explore Gale Crater on Mars. Rocknest is the group of stones seen near the top left of the above image -- just to the left of Curiosity's mast.