Scorpius in Red and Blue
25.05.2012

Cosmic dust clouds dim the light of background stars. But they also reflect the light of stars nearby. Since bright stars tend to radiate strongly in the blue portion of the visible spectrum, and the interstellar dust scatters blue light more strongly than red, the dusty reflection nebulae tend to be blue.

Nebulosity in Sagittarius
18.07.1996

What causes the colors in this beautiful nebulosity in Sagittarius? Dubbed NGC 6589 and NGC 6590, the colors of this nebulosity, are caused by gas and dust. The blue color of the nebula nearest the bright stars is caused by reflection off interstellar dust.

Starlight Reflections
14.04.1998

Wisps of dust fill the space between the stars. This dust is usually invisible, subtly acting to dim the light of more distant stars. Sometimes this dust is thick and prominent as dark patches on otherwise bright emission nebulae. Other times this dust may show itself by reflecting the light of bright, nearby stars.

Rings Around Beta Pictoris
8.02.2000

An unusual dust disk surrounds nearby star Beta Pictoris. Discovered in 1983, astronomers are still learning just how unusual this disk is. Recent images and computer simulations indicate that the disk contains several elliptical dust rings larger than our own Solar System.

A Star Where Photons Orbit
4.01.1997

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.

Jupiter, Moons, and Bees
25.09.2002

Rising before the Sun on September 4, Jupiter and an old cresent Moon gathered in the dim constellation of Cancer. Watching from a hillside near Austin, Texas, planet Earth, astrophotographer Russell Croman recorded this view of their passing as clouds gracefully dimmed the brilliant moonlight.

Our Galaxy in Stars, Gas, and Dust
28.09.2003

The disk of our Milky Way Galaxy is home to hot nebulae, cold dust, and billions of stars. The red nebulae visible in the above contrast-enhanced picture are primarily emission nebulae, glowing clouds of hydrogen gas heated by nearby, bright, young stars.

Our Galaxy in Stars, Gas, and Dust
27.09.1999

The disk of our Milky Way Galaxy is home to hot nebulae, cold dust, and billions of stars. The red nebulae visible in the above contrast-enhanced picture are primarily emission nebulae, glowing clouds of hydrogen gas heated by nearby, bright, young stars.

A Star Where Photons Orbit
26.11.1995

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 Observable Universe
8.05.2018

How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you -- is the observable universe. In visible...