Ancestor of all living things was quite complex

Prior theories held that organism was little more than crude mess of molecular parts

Manfredo Seufferheld

Researchers studied simple organisms such as this bacteria to get a clearer picture of what LUCA was like.

By Jennifer Viegas

The relative of all living things, dubbed the Last Universal Common Ancestor (LUCA), was a sophisticated organism with a complex structure recognizable as a cell, according to a new paper in the journal Biology Direct./.../

updated 10/5/2011 7:21:03 PM ET

The Cosmos' Greatest Mystery Deepens

Dark Matter, Darker Still: The Cosmos' Greatest Mystery Deepens

By MICHAEL D. LEMONICK Wednesday, Oct. 26, 2011

The galaxy of Andromeda, the nearest large galaxy to our own, circa 1990

Space Frontiers / Hulton Archive / Getty Images

• COMMENT

Like Hollywood legends Audrey Hepburn and Katharine Hepburn, dark energy and dark matter are completely unrelated, even though they share a name. Dark energy, a force that makes the universe expand faster and faster all the time, is called dark because it's mysterious. Nobody knows what it is. Dark matter, on the other hand, a type of matter that outweighs ordinary stars and galaxies 5 to 1, is called dark because it's utterly invisible. We know it's there because its gravity yanks galaxies and stars around, but it neither emits nor reflects any light.

HH-222: The Waterfall Nebula

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 October 24

HH-222: The Waterfall Nebula
Image Credit: Z. Levay (STScI/AURA/NASA), T.A. Rector (U. Alaska Anchorage) & H. Schweiker (NOAO/AURA/NSF), KPNO, NOAO

Explanation: What created the Waterfall Nebula? No one knows. The structure seen in the region of NGC 1999 in the Great Orion Molecular Cloud complex is one of the more mysterious structures yet found on the sky. Designated HH-222, the elongated gaseous stream stretches about ten light years and emits an unusual array of colors. One hypothesis is that the gas filament results from the wind from a young star impacting a nearby molecular cloud. That would not explain, however, why the Waterfall and fainter streams all appear to converge on a bright but unusual non thermal radio source located toward the upper left of the curving structure.Another hypothesis is that the unusual radio source originates from a binary system containing a hot white dwarf, neutron star, or black hole, and that the Waterfall is just a jet from this energetic system. Such systems, though, are typically strong X-rays emitters, and no X-rays have been detected. For now, this case remains unsolved. Perhaps well-chosen future observations and clever deductive reasoning will unlock the true origin of this enigmatic wisp in the future.

Astronomers: What other "mysterious structures" appear on the sky?