Collinder 399: The Coat Hanger
26.08.2015

Is this coat hanger a star cluster or an asterism? This cosmic hang-up has been debated over much of last century, as astronomers wondered whether this binocular-visible object is really a physically associated open cluster or a chance projection. Chance star projections are known as asterisms, an example of which is the popular Big Dipper.

Arp 286: Trio in Virgo
6.07.2016

A remarkable telescopic composition in yellow and blue, this scene features a trio of interacting galaxies almost 90 million light-years away, toward the constellation Virgo. On the right, two, spiky, foreground Milky Way stars echo the trio galaxy hues, a reminder that stars in our own galaxy are like those in the distant island universes.

Rings Around the Ring Nebula
15.07.2018

There is much more to the familiar Ring Nebula (M57), however, than can be seen through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure...

Peculiar Galaxies of Arp 273
19.02.2022

The spiky stars in the foreground of this backyard telescopic frame are well within our own Milky Way Galaxy. But the two eye-catching galaxies lie far beyond the Milky Way, at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters.

APOD: 2023 January 2 Б After Sunset Planet Parade
2.01.2023

Look up tonight and see a whole bunch of planets. Just after sunset, looking west, planets Venus, Saturn, Jupiter and Mars will all be simultaneously visible. Listed west to east, this planetary lineup will have Venus nearest the horizon, but setting shortly after the Sun.

An ALMA Telescope Array Time Lapse
26.05.2014

It is the most expensive and complex ground-based astronomy project ever -- what will it see tonight? The Atacama Large Millimeter Array (ALMA) project consists of 66 dishes, many the size of a small house, situated in the high altitude Atacama Desert in Northern Chile.

Pauli Exclusion Principle: Why You Don't Implode
19.02.2003

Why doesn't matter just bunch up? The same principle that keeps neutron stars and white dwarf stars from imploding also keeps people from imploding and makes normal matter mostly empty space. The observed reason is known as the Pauli Exclusion Principle.

Orion Nebula in Oxygen, Hydrogen, and Sulfur
13.07.2004

The Great Nebula in Orion, an immense, nearby starbirth region, is arguably the most famous of all astronomical nebulae. The Orion Nebula, also known as M42, is shown above through ultraviolet and blue filters augmented with three exact colors specifically emitted by hydrogen, oxygen, and sulfur.

X-ray Hot Supernova Remnant in the SMC
9.12.1999

The Q-shaped cloud seen in this false-color X-ray image from the orbiting Chandra Observatory is big ... about 40 light-years across. It's hot too, as its X-ray glow is produced by multi-million degree gas.

IC 2118: The Witch Head Nebula
11.12.2006

Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion.