Hesiodus Sunrise Ray
26.03.2010

Stark shadows of mountains and crater walls stand out along the lunar terminator, or shadow line between night and day, in this telescopic image. Of course, if viewed from the lunar surface near the terminator line, the Sun would be rising and still close to the lunar horizon.

M74: The Perfect Spiral
6.04.2011

If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces, M74 presents a gorgeous face-on view.

Milky Way Galaxy Doomed: Collision with Andromeda Pending
4.06.2012

Will our Milky Way Galaxy collide one day with its larger neighbor, the Andromeda Galaxy? Most likely, yes. Careful plotting of slight displacements of M31's stars relative to background galaxies on recent Hubble...

All of Mercury
27.04.2019

Only six years ago, the entire surface of planet Mercury was finally mapped. Detailed observations of the innermost planet's surprising crust began when the robotic have been ongoing since the robotic MESSENGER spacecraft first passed Mercury in 2008 and continued until its controlled crash landing in 2015.

Dark Matter in a Simulated Universe
24.10.2020

Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters...

Spiral Galaxy NGC 1512: The Inner Rings
7.05.2022

Most galaxies don't have any rings -- why does this galaxy have two? To begin, the bright band near NGC 1512's center is a nuclear ring, a ring that surrounds the galaxy center and glows brightly with recently formed stars.

Waves of the Great Lacerta Nebula
13.09.2022

It is one of the largest nebulas on the sky -- why isn't it better known? Roughly the same angular size as the Andromeda Galaxy, the Great Lacerta Nebula can be found toward the constellation of the Lizard (Lacerta).

Encke and the Tadpoles
26.10.2023

History's second known periodic comet is Comet Encke (2P/Encke). As it swings through the inner Solar System, Encke's orbit takes it from an aphelion, its greatest distance from the Sun, inside the orbit of Jupiter to a perihelion just inside the orbit of Mercury.

APOD: 2024 April 1 Б Swirling Magnetic Field around Our Galaxys Central Black Hole
31.03.2024

What's happening to the big black hole in the center of our galaxy? It is sucking in matter from a swirling disk -- a disk that is magnetized, it has now been confirmed. Specifically, the black hole's accretion disk has recently been seen to emit polarized light, radiation frequently associated with a magnetized source.

Shell Game in NGC 300
22.08.2002

Featured in color in yesterday's episode, big, beautiful, face-on spiral galaxy NGC 300 is seen here through a narrow filter that transmits only the red light of hydrogen atoms. Ionized by energetic starlight, a hydrogen atom emits the characteristic red H-alpha light as its single electron is recaptured and transitions to lower energy states.