Southwest Mercury
16.02.2003

The planet Mercury resembles a moon. Mercury's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron.

Unexpected Comet Pojmanski Now Visible
6.03.2006

Have you ever seen a comet? Comets bright enough to be visible to the unaided eye appear only every few years. Right now, however, a new comet has brightened unexpectedly and is visible as a faint streak to the unaided northern observer in the eastern morning sky just before sunrise. Binoculars may help.

Yutu 2 on the Farside
5.01.2019

On January 3, the Chinese Chang'e-4 spacecraft made the first successful landing on the Moon's farside. Taken by a camera on board the lander, this image is from the landing site inside Von Karman crater.

APOD: 2023 August 21 Б Introducing Comet Nishimura
21.08.2023

Will Comet Nishimura become visible to the unaided eye? Given the unpredictability of comets, no one can say for sure, but it currently seems like a good bet. The comet was discovered only ten days ago by Hideo Nishimura during 30-second exposures with a standard digital camera.

Pic du Pleiades
9.12.2023

Near dawn on November 19 the Pleiades stood in still dark skies over the French Pyrenees. But just before sunrise a serendipitous moment was captured in this single 3 second exposure; a bright meteor streak appeared to pierce the heart of the galactic star cluster.

APOD: 2024 February 11 Б Rocket Plume Shadow Points to the Moon
11.02.2024

Why would the shadow of a rocket's launch plume point toward the Moon? In early 2001 during a launch of the space shuttle Atlantis, the Sun, Earth, Moon, and rocket were all properly aligned for this photogenic coincidence.

The Belt of Venus over the Valley of the Moon
23.07.2006

Although you've surely seen it, you might not have noticed it. During a cloudless twilight, just before sunrise or after sunset, part of the atmosphere above the horizon appears slightly off-color, slightly pink.

Mercury on the Horizon
17.07.2016

Have you ever seen the planet Mercury? Because Mercury orbits so close to the Sun, it never wanders far from the Sun in Earth's sky. If trailing the Sun, Mercury will be visible low on the horizon for only a short while after sunset.

Southwest Mercury
13.02.2000

The planet Mercury resembles a moon. Mercury's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron.

A Triangular Shadow of a Large Volcano
5.07.2011

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.