Astronomy Picture Of the Day (APOD)APOD: 2023 July 31 Б Phobos over Mars
Why is Phobos so dark? Phobos, the largest and innermost of the two Martian moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.
APOD: 2023 July 30 Б Spiral Aurora over Icelandic Divide
Admire the beauty but fear the beast. The beauty is the aurora overhead, here taking the form of a great green spiral, seen between picturesque clouds with the bright Moon to the side and stars in the background.
Apollo 11: Catching Some Sun
Bright sunlight glints as long dark shadows mark this image of the surface of the Moon. It was taken fifty-four years ago, July 20, 1969, by Apollo 11 astronaut Neil Armstrong, the first to walk on the lunar surface. Pictured is the mission's lunar module, the Eagle, and spacesuited lunar module pilot Buzz Aldrin.
Young Stars, Stellar Jets
High-speed outflows of molecular gas from a pair of actively forming young stars shine in infrared light, revealing themselves in this NIRcam image from the James Webb Space Telescope. Cataloged as HH (Herbig-Haro) 46/47, the young stars are lodged within a dark nebula that is largely opaque when viewed in visible light.
Galaxies in the River
Large galaxies grow by eating small ones. Even our own galaxy engages in a sort of galactic cannibalism, absorbing small galaxies that are too close and are captured by the Milky Way's gravity.
APOD: 2023 July 26 Б IC 4628: The Prawn Nebula
South of Antares, in the tail of the nebula-rich constellation Scorpius, lies emission nebula IC 4628. Nearby hot, massive stars, millions of years young, irradiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow, dominated by the red emission of hydrogen.
APOD: 2023 July 25 Б The Eagle Nebula with Xray Hot Stars
What do the famous Eagle Nebula star pillars look like in X-ray light? To find out, NASA's orbiting Chandra X-ray Observatory peered in and through these interstellar mountains of star formation.
APOD: 2023 July 24 Б Chemicals Glow as a Meteor Disintegrates
Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured here is a fireball, a disintegrating meteor that was not only one of the brightest the photographer has ever seen, but colorful.
APOD: 2023 July 23 Б The Antikythera Mechanism
It does what? No one knew that 2,000 years ago, the technology existed to build such a device. The Antikythera mechanism, pictured, is now widely regarded as the first computer. Found...
Apollo 11: Armstrong's Lunar Selfie
A photograph of Buzz Aldrin standing on the Moon taken by Neil Armstrong, was digitally reversed to create this lunar selfie. Captured in July 1969 following the Apollo 11 moon landing, Armstrong's original photograph recorded not only the magnificent desolation of an unfamiliar world, but Armstrong himself reflected in Aldrin's curved visor.