Retrograde Mars
13.06.2010

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

A Waterspout in Florida
16.05.2020

What's happening over the water? Pictured here is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water. Waterspouts are spinning columns of rising moist air that typically form over warm water.

M31: The Andromeda Galaxy
18.01.2022

The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy. Even at some two and a half million light-years distant, this immense spiral galaxy -- spanning over 200,000 light years -- is visible, although as a faint, nebulous cloud in the constellation Andromeda.

APOD: 2023 September 5 Б Blue Supermoon Beyond Syracuse
4.09.2023

The last full moon was doubly unusual. First of all, it was a blue moon. A modern definition of a blue moon is a second full moon to occur during one calendar month. Since there are 13 full moons in 2023, one month has to have two -- and that month was August.

APOD: 2026 June 27 Б Mars Marathon by Perseverance
26.06.2026

In this recent HiRISE view from the Mars Reconnaissance Orbiter, the little green dot indicated on the surface of the big Red Planet is the Perseverance Mars rover. Recorded on June 13, the car-sized...

W5: Pillars of Star Formation
15.12.2014

How do stars form? Images of the star forming region W5 like those in the infrared by NASA's Wide Field Infrared Survey Explorer (WISE) satellite provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges.

Around The Arches Cluster
14.06.2001

The most compact cluster of stars known in our galaxy, the Arches cluster, boasts 100 or so massive, young stars contained within a diameter of one light-year. Seen toward the constellation Sagittarius, the Arches...

Stephan s Quintet Plus One
27.03.2014

The first identified compact galaxy group, Stephan's Quintet is featured in this remarkable image constructed with data drawn from Hubble Legacy Archive and the Subaru Telescope on the summit of Mauna Kea.

A Star Where Photons Orbit
25.11.1995

The above computer animated picture depicts how a very compact star would look to a nearby observer. The star pictured is actually more compact that any known except a black hole, so it is only hypothetical. The observer is situated at the photon sphere, where photons can orbit in a circle.

The Sombrero Galaxy in Infrared
11.05.2005

This floating ring is the size of a galaxy. In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.