Introducing Comet Garradd
27.07.2011

Another large snowball is falling toward the Sun. Comet Garradd was discovered two years ago by Gordon Garradd in Australia, and is currently visible through a small telescope at visual magnitude nine. Officially designated...

APOD: 2025 October 3 Б Pandora's Cluster of Galaxies
3.10.2025

This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 recorded by the James Webb Space Telescope's NIRCam. Also dubbed Pandora's Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters. It lies some 3.5 billion light-years away, toward the constellation Sculptor.

Comet Hyakutake and a Tree
10.04.1996

Comet Hyakutake is still visible as it continues its orbit around the Sun. The comet will brighten again in late April and early May. The above fascinating picture was taken with a three minute exposure. In the middle of the exposure, the photographer cleverly set off a flash, momentarily illuminating the foreground tree.

Comet NEOWISE Rising over the Adriatic Sea
13.07.2020

This sight was worth getting out of bed early. Comet C/2020 F3 (NEOWISE) has been rising before dawn during the past week to the delight of northern sky enthusiasts awake that early. Up before...

HUDF Infrared: Dawn of the Galaxies
9.12.2009

When did galaxies form? To help find out, the deepest near-infrared image of the sky ever has been taken of the same field as the optical-light Hubble Ultra Deep Field (HUDF) in 2004. The new image was taken this summer by the newly installed Wide Field Camera 3 on the refurbished Hubble Space Telescope.

Cosmic Microwave Map Swirls Indicate Inflation
18.03.2014

Did the universe undergo an early epoch of extremely rapid expansion? Such an inflationary epoch has been postulated to explain several puzzling cosmic attributes such as why our universe looks similar in opposite directions.

Simulation: Formation of the First Stars
30.06.2021

How did the first stars form? To help find out, the SPHINX computer simulation of star formation in the very early universe was created, some results of which are shown in the featured video. Time since the Big Bang is shown in millions of years on the upper left.

The Supernova and Cepheids of Spiral Galaxy UGC 9391
6.06.2016

What can this galaxy tell us about the expansion rate of the universe? Perhaps a lot because UGC 9391, featured, not only contains Cepheid variable stars (red circles) but also a recent Type Ia supernova (blue X).

Abell 1795: A Galaxy Cluster s Cooling Flow
8.12.2000

Throughout the Universe, galaxies tend to swarm in groups ranging from just a handful of members to casts of thousands. Astronomers have realized since the early 1970s that the larger swarms, immense clusters of galaxies millions of light-years across, are immersed within tenuous clouds of hot gas which glow strongly in x-rays.

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.