The Horsehead and Flame Nebulas
3.11.2021

The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the orange emission nebula at the far right of the featured picture. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright emission nebula.

A Force from Empty Space: The Casimir Effect
1.08.2004

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

A Force from Empty Space: The Casimir Effect
17.12.2006

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

Prometheus Rising Through Saturns F Ring
19.10.2010

What is that dark streak below Prometheus? Although it may look like a shadow or a trail blazed by sweeping up material, computer simulations indicate that the dark streak is better understood as an empty path pulled away by the gravity of Saturn's small moon.

Third Millennium, First Eclipse
4.01.2001

The first eclipse of the third millennium is coming up! A total lunar eclipse mainly visible from Europe, Asia, and Africa, will occur on January 9th as the full Moon glides through the long, but not so dark shadow of planet Earth. Why not so dark?

Martian Moon Phobos from Mars Express
1.12.2010

Why is Phobos so dark? Phobos, the largest and innermost of two Martian moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.

Martian Moon Phobos from Mars Express
8.11.2020

Why is Phobos so dark? Phobos, the largest and innermost of two Martian moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.

Unexpected Galaxy String in the Early Universe
20.01.2004

How could such a long string of galaxies form so early in the universe? Several new measurements of galaxies and clusters in the early universe are reporting structures involving galaxies and clusters that are larger than expected with the new standard "dark-energy" cosmology.

Molecular Cloud Barnard 68
9.04.2006

Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars.

A Force from Empty Space: The Casimir Effect
6.12.2015

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.