XMM Launched
21.12.1999

X-ray astronomy entered a golden age earlier this month with the successful launch of the X-ray Multi-Mirror (XMM) satellite. XMM's three huge telescope barrels each hold 58 concentric cylindrical mirrors, together totaling a surface area rivaling a tennis court.

A Partial Eclipse Over Manila Bay
20.05.2012

What's happened to the setting Sun? An eclipse! In early 2009, the Moon eclipsed part of the Sun as visible from parts of Africa, Australia, and Asia. In particular the above image, taken from the Mall of Asia seawall, caught a partially eclipsed Sun setting over Manila Bay in the Philippines.

Asteroid 2012 DA14 Passes the Earth
17.02.2013

There it goes. That small spot moving in front of background stars in the above video is a potentially dangerous asteroid passing above the Earth's atmosphere. This past Friday, the 50-meter wide asteroid...

Giant Cluster Bends Breaks Images
23.08.2015

What are those strange blue objects? Many of the brightest blue images are of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies. Cluster galaxies here typically appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.

Reflections on the 1970s
13.01.2016

The 1970s are sometimes ignored by astronomers, like this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula.

Io: Moon over Jupiter
7.08.2016

How big is Jupiter's 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.

Moon and Venus Appulse over a Tree
6.02.2019

What's that bright spot near the Moon? Venus. About a week ago, Earth's Moon appeared unusually close to the distant planet Venus, an angular coincidence known as an appulse. Similar to a conjunction, which is a coordinate term, an appulse refers more generally to when two celestial objects appear close together.

A Desert Eclipse
13.01.2020

A good place to see a ring-of-fire eclipse, it seemed, would be from a desert. In a desert, there should be relatively few obscuring clouds and trees. Therefore late last December a group...

APOD: 2025 January 27 Б Pleiades over Half Dome
27.01.2025

Stars come in bunches. The most famous bunch of stars on the sky is the Pleiades, a bright cluster that can be easily seen with the unaided eye. The Pleiades lies only about 450 light years away, formed about 100 million years ago, and will likely last about another 250 million years.

Rotating Titan in Infrared Light
15.02.2006

Titan is one of the strangest places in our Solar System. The only moon known with thick clouds, this unusual satellite of Saturn shows evidence of evaporating lakes created by methane rain. The clouds...