Stereo Helene
29.03.2025

Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is a Trojan moon, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case Saturn and larger moon Dione.

Flying Over Asteroid Eros West End
17.04.2000

The robot spacecraft NEAR Shoemaker continues to orbit asteroid Eros. This condensed 40-minute long time-lapse sequence taken last month shows what it looks like to pass within 200 kilometers of Eros' west end. The north pole of the rotating mountain is toward the bottom of the picture.

A Black Hole in M87's Center?
5.03.1996

The center of nearby giant galaxy M87 is a dense and violent place. In this 1994 photograph by the Hubble Space Telescope, a disk of hot gas was found to be orbiting at the center of this massive elliptical galaxy. The disk is evident on the lower left of the above photograph.

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.

APOD: 2024 August 11 Б Animation: Perseid Meteor Shower
11.08.2024

Where do Perseid meteors come from? Mostly small bits of stony grit, Perseid meteoroids were once expelled from Comet Swift-Tuttle and continue to follow this comet's orbit as they slowly disperse. The featured animation depicts the entire meteoroid stream as it orbits our Sun.

At Last, GLAST
13.06.2008

Rising through a billowing cloud of smoke, this Delta II rocket left Cape Canaveral Air Force Station's launch pad 17-B Wednesday at 12:05 pm EDT. Snug in the payload section was GLAST, the Gamma-ray Large Area Space Telescope, now in orbit around planet Earth.

Eclipse over Chongqing, China
24.07.2009

The daytime sky grew dark, the temperature dropped, and lights came on as Chongqing, China, was plunged into the Moon's shadow during the July 22nd total solar eclipse. This serene, wide-angle view of the event looks to the east over the large, populous city from a newly constructed park.

Into the Void
6.06.2015

Fifty years ago, on June 3, 1965, Edward White stepped out of the orbiting Gemini 4 spacecraft to become the first US astronaut to walk in space. White is captured in this photo taken...

CMB Dipole: Speeding Through the Universe
3.04.2022

Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies.

APOD: 2025 October 20 Б Finding Comet Lemmon
20.10.2025

Tonight, if you can see the stars of the Big Dipper, then you can find comet Lemmon in your evening sky. After sunset, look for the faint but extended comet above your northwestern horizon -- but below the handle of the famous celestial kitchen utensil of the north.