Mercurys Sodium Tail
8.07.2020

What is that fuzzy streak extending from Mercury? Long exposures of our Solar System's innermost planet may reveal something unexpected: a tail. Mercury's thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun. Sunlight also liberates these molecules from Mercury's surface and pushes them away.

The Butterfly Nebula from Hubble
21.11.2022

Stars can make beautiful patterns as they age -- sometimes similar to flowers or insects. NGC 6302, the Butterfly Nebula, is a notable example. Though its gaseous wingspan covers over 3 light-years and its estimated...

Spiral Galaxy NGC 3310 in Ultraviolet
17.01.2001

Why is NGC 3310 bursting with young stars? The brightest of these new stars are so hot that they light up this spiral galaxy not only in blue light, but in light so blue humans can't see it: ultraviolet. The Hubble Space Telescope took the above photograph in different bands of ultraviolet light.

Zodiacal Light Over Laguna Verde
29.10.2009

An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.

Partial Solar Eclipse with Airplane
13.05.2013

It was just eight minutes after sunrise, last week, and already there were four things in front of the Sun. The largest and most notable was Earth's Moon, obscuring a big chunk of the Sun's lower limb as it moved across the solar disk, as viewed from Fremantle, Australia.

Baryon Acoustic Oscillations from SDSS III
20.01.2014

How large do things appear when far away? When peering across the universe, the answer can actually tell us about its average gravitational history and hence its composition. Toward this goal, the Baryon Oscillation...

The Missing Craters of Asteroid Itokawa
9.02.2014

Where are the craters on asteroid Itokawa? Missing -- unexpectedly. The Japanese robot probe Hayabusa approached the Earth-crossing asteroid in 2005 and returned pictures showing a surface unlike any other Solar System body yet photographed -- a surface possibly devoid of craters.

Aurora Dog over Alaska
29.04.2014

Sometimes it is hard to believe what you see in the sky. While leading his annual aurora tour last month near Fairbanks in central Alaska, astrophotographer John Chumack and his company saw a most unusual aurora. This bright aurora appeared to change into the shape of a jumping dog, complete with a curly tail.

M2 9: Wings of a Butterfly Nebula
24.07.2016

Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes.

APOD: 2025 February 9 Б Milky Way over the Australian Pinnacles
9.02.2025

What strange world is this? Earth. In the foreground of the featured image are the Pinnacles, unusual rock spires in Nambung National Park in Western Australia. Made of ancient sea shells (limestone), how these human-sized picturesque spires formed remains unknown.