The Dark River to Antares
3.06.2008

Connecting the Pipe Nebula to the bright star Antares is a flowing dark cloud nicknamed the Dark River. The murkiness of the Dark River is caused by absorption of background starlight by dust, although the nebula contains mostly hydrogen and molecular gas.

NGC 6334: The Cats Paw Nebula
12.09.2017

Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius.

A Mercury Transit Sequence
27.05.2003

Earlier this month, the planet Mercury crossed the face of the Sun, as seen from Earth. Because the plane of Mercury's orbit is not exactly coincident with the plane of Earth's orbit, Mercury usually appears to pass over or under the Sun.

Black Holes and Galactic Centers
13.01.1997

Do all galaxies have black holes at their centers? Although not even a single galaxy has yet been proven to have a central black hole, the list of candidates has increased yet again. Recent...

A Partial Lunar Eclipse
28.06.2010

What's happened to the Moon? This past weekend, once again, part of the Moon moved through the Earth's shadow. This happens about once or twice a year, on the average, but not each month since the Moon's orbit around the Earth is slightly tilted.

Milky Way Above Easter Island
18.06.2012

Why were the statues on Easter Island built? No one is sure. What is sure is that over 800 large stone statues exist there. The Easter Island statues, stand, on the average, over twice as tall as a person and have over 200 times as much mass.

Hunter s Moon over the Alps
3.11.2012

A Full Moonset can be a dramatic celestial sight, and Full Moons can have many names. Late October's Full Moon, the second Full Moon after the northern hemisphere autumnal equinox, has been traditionally called the Hunter's Moon.

Gamma Ray Crab, Geminga
24.06.1995

What if you could "see" in gamma-rays? If you could, these two spinning neutron stars or pulsars would be among the brightest objects in the sky. This computer processed image shows the Crab Nebula pulsar (below and right of center) and the Geminga pulsar (above and left of center) in the "light" of gamma-rays.

A Green Flash from the Sun
9.11.2002

Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood.

Comet Halley and the Milky Way
3.10.1997

Comet Halley was photographed superposed in front of the disk of our Milky Way Galaxy in 1986 by the Kuiper Airborne Observatory. Comet Halley is the bright white streak near this photograph's center. Comet Halley is the most famous comet in history, and returns to the inner Solar System every 76 years.