NGC 1999: Reflection Nebula In Orion
2.03.2000

A dusty bright nebula contrasts dramatically with a dusty dark nebula in this Hubble Space Telescope image recorded shortly after December's orbital servicing mission. The nebula, cataloged as NGC 1999, is a reflection nebula, which shines by reflecting light from a nearby star.

Anemic Spiral NGC 4921 from Hubble
15.05.2019

How far away is spiral galaxy NGC 4921? It's surpringly important to know. Although presently estimated to be about 300 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe.

Hubble's Constant And The Expanding Universe (II)
14.05.1996

In this century, the discovery that the Universe is expanding has produced a revolution in human thought about the Cosmos. American astronomer Edwin Hubble played a major role in this profound discovery, coining the "Hubble constant".

LL Orionis: When Cosmic Winds Collide
22.05.2016

What created this great arc in space? This arcing, graceful structure is actually a bow shock about half a light-year across, created as the wind from young star LL Orionis collides with the Orion Nebula flow.

Optical Transient Near GRB970508 Shows Distant Redshift
13.05.1997

The GRB distance scale controversy may have just ended with a flash. Gamma Ray Bursts (GRBs) are powerful explosions occurring in seemingly random positions on the sky. They are so featureless and so poorly resolved, however, that their distances could not be determined.

Fermi s Gamma Ray Sky
21.03.2009

Scanning the entire sky in gamma-rays, photons with over 50 million times the energy of visible light, the Fermi mission's Large Area Telescope (LAT) explores the high-energy universe. This all-sky map constructed from...