On the Origin of Gold
15.10.2017

Where did the gold in your jewelry originate? No one is completely sure. The relative average abundance in our Solar System appears higher than can be made in the early universe, in stars, and even in typical supernova explosions.

Globular Cluster M2
11.06.2001

Beneath the south pole of our Milky Way Galaxy lies a ball of over 100,000 stars. M2, the second object on Charles Messier's eighteenth century list of bright diffuse sky objects...

APOD: 2025 December 29 Б M1: The Crab Nebula
29.12.2025

This is the mess that is left when a star explodes. The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments. The filaments are not only tremendously...

Anemic Galaxy NGC 4921 at the Edge
9.02.2009

How far away is spiral galaxy NGC 4921? Although presently estimated to be about 320 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.

The Hubble Deep Field in Infrared
12.10.1998

Galaxies this faint have never been seen before. In 1996 the Hubble Space Telescope (HST) created one of the most famous pictures of modern astronomy, the Hubble Deep Field (HDF). Now HST has returned to a piece of the HDF for a long exposure by its new NICMOS camera, sensitive to infrared light.

GRB 090423: The Farthest Explosion Yet Measured
29.04.2009

An explosion so powerful it was seen clear across the visible universe was recorded in gamma-radiation last week by NASA's orbiting Swift Observatory. Farther than any known galaxy, quasar, or optical supernova, the gamma-ray burst recorded last week was clocked at redshift 8.2, making it the farthest explosion of any type yet detected.

Arecibo: The Largest Telescope
9.03.1996

The Arecibo radio telescope is currently the largest single-dish telescope in the world. First opening in 1963, this 305 meter (1000 foot) radio telescope resides in a natural valley of Puerto Rico. The Arecibo...

Anemic Spiral NGC 4921 from Hubble
25.11.2013

How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 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.

The Century that Defined Galaxy
30.12.1999

As the twentieth century dawned a debate raged over whether the Milky Way was the entire universe. The 1920s brought observations of spiral-nebulae that housed familiar but faint variable stars, and hence placed these nebulae much farther than anything else ever found. The Milky Way, apparently, is itself a spiral nebula seen from the inside.

The 100 Meter Green Bank Radio Telescope
11.03.2002

The largest single-dish fully steerable radio telescope began operation in 2000 August in Green Bank, West Virginia, USA. Dedicated as the Robert C. Byrd Green Bank Telescope, the device weighs over 30 times more than the Statue of Liberty, and yet can point anywhere in the sky more precisely than one thousandth of a degree.