A Fire Rainbow over West Virginia
30.08.2021

What's happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating prisms. Known informally as a fire rainbow for its flame-like appearance, a circumhorizon arc appears parallel to the horizon.

A Star Cluster in Motion
30.07.2002

Star clusters are a swarm of complex motions. The stars that compose globular clusters and many open clusters all orbit the cluster center, occasionally interacting, gravitationally, with a close-passing star. The orbits of stars around the cluster are typically not as circular as the orbits of planets in our solar system.

GRO J1655 40: Evidence for a Spinning Black Hole
1.06.2003

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.

Seven Leonids Over Wise Observatory
24.11.1998

More Leonids were visible at some places than others. In Israel, early in the morning of 17 November, it rained meteors though a clear sky. Observers there reported a peak rate for the 1998 Leonid Meteor Shower of about 600 meteors per hour.

Pluto: The Frozen Planet
13.02.1999

This portrait of Pluto and its companion Charon was taken by the Hubble Space Telescope in 1994. Pluto is usually the most distant planet from the Sun but because of its eccentric orbit Pluto crossed inside of Neptune's orbit in 1979.

An Anomalous SETI Signal
30.03.1999

No one knows for sure what caused this signal. The bright colors on the blue background indicate that an anomalous signal was received here on Earth by a radio telescope involved in a Search for Extraterrestrial Intelligence (SETI). A search for these signals is ongoing by several groups including volunteer members of the SETI League.

The View Near a Black Hole
19.04.2009

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.

Evaporating Blobs of the Carina Nebula
23.04.2012

No, they are not alive -- but they are dying. The unusual blobs found in the Carina nebula, some of which are seen floating on the upper right, might best be described as evaporating. Energetic light and winds from nearby stars are breaking apart the dark dust grains that make the iconic forms opaque.

A Circumhorizontal Arc Over Ohio
24.05.2014

Why would clouds appear to be different colors? The reason here is that ice crystals in distant cirrus clouds are acting like little floating prisms. Sometimes known as a fire rainbow for its flame-like appearance, a circumhorizon arc lies parallel to the horizon.

APOD: 2023 November 29 Б A Landspout Tornado over Kansas
29.11.2023

Could there be a tornado inside another tornado? In general, no. OK, but could there be a tornado inside a wider dust devil? No again, for one reason because tornados comes down from the sky, but dust devils rise up from the ground.