NGC 4603 and the Expanding Universe
27.05.1999

NGC 4603, a galaxy with majestic spiral arms and intricate dust lanes, is 108 million light-years away. Its distance has been accurately measured by astronomers using one of the fundamental yardsticks of the extragalactic distance scale - pulsating variable stars known as Cepheids.

APOD: 2025 August 24 Б The Spinning Pulsar of the Crab Nebula
24.08.2025

At the core of the Crab Nebula lies a city-sized, magnetized neutron star spinning 30 times a second. Known as the Crab Pulsar, it is the bright spot in the center of the gaseous swirl at the nebula's core.

A 2000 Leonid Through Orion
20.11.2000

The Leonid Meteor Shower this year could be described as good but not great. During November 17 and 18 the Earth crossed through several streams of sand-sized grit left orbiting the Sun by Comet Tempel-Tuttle. Several distinct peaks in meteor activity were reported, with

Cepheus 1: Nearby Galaxy Hiding
1.12.1998

Some galaxies are hard to find. Besides being hidden behind the dust and bright foreground stars of our Milky Way Galaxy, recently discovered Cepheus 1 was missed previously because it is so uniformly dim.

Antares and Rho Ophiuchi
22.09.1997

Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.

3D Mercury Transit
25.11.2006

Mercury is now visible shortly before dawn, the brightest "star" just above the eastern horizon. But almost two weeks ago Mercury actually crossed the face of the Sun for the second time in the 21st century.

Amazing Comet Holmes
24.10.2008

One year ago, Comet 17P/Holmes amazed sky watchers across planet Earth. A stunningly rapid outburst transformed it from a faint comet quietly orbiting the Sun with a period of about 7 years to a naked-eye comet rivaling the brighter stars in the constellation Perseus.

Comet Lulin and Distant Galaxies
7.03.2009

Now fading in our night sky, Comet Lulin has provided some lovely cosmic vistas. Moving rapidly against the background of stars, Lulin briefly posed with the likes of Saturn, and Regulus (Alpha Leo). But here it is seen against a field of distant galaxies.

Framed by Clouds
30.04.2009

Last Sunday's fading evening twilight featured a young crescent Moon along the western horizon. The young Moon also shared the sky with the lovely Pleiades star cluster and wandering planet Mercury. Framed by clouds in this serene skyscape from Selsey, UK, a similar twilight scene was visible around the globe.

Colorful Clouds Near Rho Ophiuchi
28.08.2012

Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.