What are Comet Tails Made Of?
26.03.1996

The tail of comet Hyakutake, visible in this recent color image, is composed of dust and gas driven off the icy comet nucleus by the Sun's heat and blown away by the solar wind. Bathed in solar ultraviolet light, the gas molecules break down and are excited, producing a characteristic glow.

Kitt Peak National Observatory
18.01.1999

At the top of Kitt Peak Mountain near Tucson, Arizona lies one of the world's great collections of telescopes. As pictured, in the dome at the far left lies the 3.5-meter WIYN Telescope, famous recently for tracking distant supernovae.

Fresh Tiger Stripes on Saturns Enceladus
27.04.2020

How will humanity first learn of extraterrestrial life? One possibility is to find it under the icy surface of Saturn's moon Enceladus. A reason to think that life may exist there are long features -- dubbed tiger stripes -- that are known to be spewing ice from the moon's icy interior into space.

Central Lagoon in Infrared
19.03.2021

Stars fill this infrared view, spanning 4 light-years across the center of the Lagoon Nebula. Visible light images show the glowing gas and obscuring dust clouds that dominate the scene. But this infrared image...

W5: Pillars of Star Formation
20.11.2011

How do stars form? A study of star forming region W5 by the sun-orbiting Spitzer Space Telescope provides clear clues by recording that massive stars near the center of empty cavities are older than stars near the edges.

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.

A Happy Sky over Los Angeles
12.11.2017

Sometimes, the sky may seem to smile over much of planet Earth. On this day in 2008, visible the world over, was an unusual superposition of our Moon and the planets Venus and Jupiter.

Striped Sand Dunes on Mars
6.01.2021

Why are these sand dunes on Mars striped? No one is sure. The featured image shows striped dunes in Kunowsky Crater on Mars, photographed recently with the Mars Reconnaissance OrbiterБs HiRISE Camera. Many Martian dunes are known to be covered unevenly with carbon dioxide (dry ice) frost, creating patterns of light and dark areas.

Animation: Odd Radio Circles
30.03.2022

What do you call a cosmic puzzle that no one expected to see? In this case, Odd Radio Circles, aka ORCs. ORC-1 typifies the enigmatic five objects, only visible at radio frequencies, that were serendipitously discovered in 2019 using the new Australian SKA Pathfinder radio array.

M51 in 255 Hours
11.08.2023

An intriguing pair of interacting galaxies, M51 is the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with whirlpool-like spiral structure seen nearly face-on is also cataloged as NGC 5194. Its spiral arms and dust lanes sweep in front of a companion galaxy (right), NGC 5195.