A Network of Microlensing Caustics
24.08.1999

A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic.

APOD: 2023 November 6 Б Red Aurora over Italy
6.11.2023

What was that red glow on the horizon last night? Aurora. Our unusually active Sun produced a surface explosion a few days ago that sent out a burst of electrons, protons, and more massive charged nuclei.

An Active Night over the Magellan Telescopes
21.02.2017

The night sky is always changing. Featured here are changes that occurred over a six hour period in late 2014 June behind the dual 6.5-meter Magellan Telescopes at Las Campanas Observatory in Chile.

GRB010222: Gamma Ray Burst, X Ray Afterglow
13.04.2001

A fading afterglow from one of the most powerful explosions in the universe is centered in this false color image from the spacebased Chandra X-ray Observatory. The cosmic explosion, an enormously bright gamma-ray burst (GRB), originated in a galaxy billions of light-years away and was detected by the BeppoSAX satellite on February 22.

Historic Optical Flash Fades
22.04.1997

The largest telescopes in the world have scrambled to point toward this faint, fading object. Why? Because it may well be the first active optical counterpart ever found for a gamma-ray burst, and could hold the clue to the distance scale to this most enigmatic class of astronomical objects.

IC 1396 Close Up
30.09.2005

Clouds of glowing hydrogen gas mingle ominously with dark dust lanes in this close-up of IC 1396, an active star forming region some 2,000 light years away in the constellation Cepheus. In this and other similar emission nebulae, energetic ultraviolet light from a hot young star strips electrons from the surrounding hydrogen atoms.

Milky Way Auroral Flower
18.10.2022

Could the stem of our Milky Way bloom into an auroral flower? No, not really, even though it may appear that way in todayБs featured all-sky image. On the left, the central plane of our home galaxy extends from the horizon past the middle of the sky.

APOD: 2024 October 1 Б Porphyrion: The Longest Known Black Hole Jets
1.10.2024

How far can black hole jets extend? A new record was found just recently with the discovery of a 23-million light-year long jet pair from a black hole active billions of years ago. Dubbed...