Comet Leonard Before Star Cluster M3
12.12.2021

Comet Leonard is now visible to the unaided eye -- but just barely. Passing nearest to the Earth today, the comet is best seen this week soon after sunset, toward the west, low on the horizon.

Arp 240: A Bridge between Spiral Galaxies from Hubble
28.11.2016

Why is there a bridge between these two spiral galaxies? Made of gas and stars, the bridge provides strong evidence that these two immense star systems have passed close to each other and experienced violent tides induced by mutual gravity.

From the Galactic Plane through Antares
2.07.2018

Behold one of the most photogenic regions of the night sky, captured impressively. Featured, the band of our Milky Way Galaxy runs diagonally along the far left, while the colorful Rho Ophiuchus region including...

Pleiades Star Cluster
20.06.1995

The Pleiades star cluster, M45, is one of the brightest star clusters visible in the northern hemisphere. It consists of many bright, hot stars that were all formed at the same time within a large cloud of interstellar dust and gas.

Illustris Simulation of the Universe
23.02.2020

How did we get here? Click play, sit back, and watch. A computer simulation of the evolution of the universe provides insight into how galaxies formed and perspectives into humanity's place in the universe.

APOD: 2023 December 31 Б Illustris: A Simulation of the Universe
31.12.2023

How did we get here? Click play, sit back, and watch. A computer simulation of the evolution of the universe provides insight into how galaxies formed and perspectives into humanity's place in the universe.

Illustris Simulation of the Universe
12.05.2014

How did we get here? Click play, sit back, and watch. A new computer simulation of the evolution of the universe -- the largest and most sophisticated yet produced -- provides new insight into how galaxies formed and new perspectives into humanity's place in the universe.

NGC 4697: X Rays from an Elliptical Galaxy
17.06.2002

The many bright, point-like sources in this Chandra Observatory x-ray image lie within NGC 4697, an elliptical galaxy some 40 million light-years away towards Virgo. Like other normal elliptical galaxies, NGC 4697 is a spherical ensemble of mainly older, fainter, low mass stars, with little star forming gas and dust compared to spiral galaxies.

Galaxy Cluster in the Early Universe
26.02.2004

Long before medieval alchemists dreamed of transmuting base metals to gold, stellar furnaces in this massive cluster of galaxies - cataloged as RDCS 1252.9-2927 - had transformed light elements into heavy ones. In the false-color composite image individual cluster galaxies can be seen at optical and near-infrared wavelengths, shown in red, yellow, and green colors.

Massive Stars in Open Cluster Pismis 24
19.12.2006

How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it a record holder.