APOD: 2024 February 19 Б Looking Sideways from the Parker Solar Probe
19.02.2024

What's happening near the Sun? To help find out, NASA launched the robotic Parker Solar Probe (PSP) to investigate regions closer to the Sun than ever before. The PSP's looping orbit brings it nearer to the Sun each time around -- every few months.

A Redshift Lookup Table for our Universe
8.04.2013

How far away is "redshift six"? Although humans are inherently familiar with distance and time, what is actually measured for astronomical objects is redshift, a color displacement that depends on exactly how energy density has evolved in our universe.

The 37 Cluster
18.11.2005

For the mostly harmless denizens of planet Earth, the brighter stars of open cluster NGC 2169 seem to form a cosmic 37. (Did you expect 42?.) Of course, the improbable numerical asterism appears solely by chance and lies at an estimated distance of 3,600 light-years toward the constellation Orion.

Analemma over the Ukraine
17.06.2007

If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma.

Aurora Persei
9.08.2008

Dark skies are favored for viewing meteor showers -- so the best viewing of this year's Perseids will occur in the early morning. While the Perseid meteor shower is scheduled to peak over...

GRO J1655 40: Evidence for a Spinning Black Hole
5.09.2010

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.

The Trail of a Minotaur
21.11.2013

Star trails arc above a moonlit beach and jetty in this serene sea and night skyscape. Captured on November 19, the single time exposure looks south down the Atlantic coast from Cape Cod, Massachusetts, USA.

Tutulemma: Solar Eclipse Analemma
22.08.2016

If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun's position change? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma.

Comet 45P Passes Near the Earth
12.02.2017

A large snowball has just passed the Earth. Known as Comet 45P/HondaMrkosPajduАkovА", or 45P for short, the comet came 10 times closer to Earth yesterday than the Earth ever gets to the Sun. During this passage, the comet was photographed sporting a thin ion tail and a faint but expansive green coma.

APOD: 2025 October 15 Б Rocket Launch Plume over Tucson
15.10.2025

Yes, but can your sunset do this? Looking west from Tucson, Arizona, USA one day last month, the sunset sky looked strange when it briefly lit up with the plume of a rocket launched from California a few minutes earlier.