Dusty Solar Systems Have "Lived-In Look"

Parts of the dust ring around our Solar System appear blue in this false-color image. This dust is now believed to be residue from collisions of Kuiper belt objects. Dust from our galaxy shows up as a band running across the center. This composite image, from the COBE satellite, is from three far-infrared wavelengths. -- Space Telescope Science Institute, COBE/DIRBE, & NASA

Out beyond the orbit of Neptune, in the perpetually cold Kuiper belt, icy objects collide and produce dust. The dust spreads out into a donut, and the inner edge reaches the orbit of Saturn. Due to the vastness of this ring around the Solar System, there is only 1 dust particle per 50-cubic-kilometers of space. This density might not be noticeable to someone orbiting the belt, but viewed from afar, it forms an infrared ring around our system.

European Space Agency (ESA) scientists discovered the ring by examining data on dust particles from the solar orbiting Ulysses and solar system transiting Pioneer probes. They concluded that the dust was not produced by the planets or from outside our system. By process of elimination, the Kuiper belt was fingered as the production site for the dust.

"... the dust has to come from somewhere."

--Malcolm Fridlund, ESA Darwin project

These results have implications for scientists working on future missions to detect planets around other suns. Dust rings around main sequence stars, like our Sun, may get special scrutiny in the search for extra-solar planets. "If we see gaps in the dust ring, it will probably have planets which are sweeping away the dust as they orbit," says Markus Landgraf of ESA's Space Operations Centre. According to Malcolm Fridlund, an ESA scientist working on the Darwin planet imager, "If you have a dust disc around a star that's not particularly young, then it's extremely interesting because the dust has to come from somewhere. The only explanation is that the star has planets, comets, asteroids or other bodies that collide and generate the dust."

Where there are planets, there may be life. Vega and Epsilon Eridani are two stars known to have dust rings that shine in the infrared wavelengths.

More information:

ESA; Feb. 18, 2002; Press Release: "ESA Scientist Discovers a Way to Shortlist Stars That Might Have Planets"

Right Universe, Wrong Color

In January of this year, researchers at Johns Hopkins University revealed the color of the Universe: green (See 01.15.02 NewsNotes: "How Green is My Universe?"). This was based on the summation of data from the Australian 2dF Galaxy Redshift Survey. The "Color of the Universe" story was widely distributed by the news media and caught the attention of Mark Fairchild, of the Munsell Color Science Laboratory at the Rochester Institute of Technology. Fairchild, an expert on the science of color perception, contacted the researchers.

Fairchild and others at Munsell examined the data and determined the "white point" for color rendition -- the point at which light appears white -- was set as if the Universe was being viewed in red light. This left the Johns Hopkins researchers "red" in the face!

"Universal" Beige!

Munsell Color Laboratories have plans to generate an accurate rendition of the color of the universe and let people judge the true color by eye. But don't get too excited, reanalysis of the Johns Hopkins data, with the white point set for an observer in a dark room, indicates the Universe is boring beige -- the color of many computer cases.

More information:

Johns Hopkins University; Mar. 7, 2002; Press Release: "Color of the Universe Corrected by Astronomers"

Signal from Beyond

Pioneer 10 -- USPS

Scientists, at a 70-meter diameter radio dish in Madrid, Spain, detected intelligent signals from deep space in early March. While the acquisition and deciphering of the message was not completely predestined, it was not unexpected. The transmission was a reply to a request, beamed into space 22-hours earlier, by the Goldstone radio dish in California.

I'll end the suspense as to the distant party in the conversation: the cosmic exchange, that began on Friday, March 1, 2002, was between dishes of the Jet Propulsion Laboratory's (JPL) Deep Space Network and Pioneer 10. The exchange was to mark the 30th anniversary of the intrepid probe's launch on March 2, 1972. (See NewsNotes for 12.01.00: "A Pioneer Continues to Break New Ground".) JPL's prior contacts with Pioneer 10 were in April and July of 2001. A contact attempt in August of 2000 failed, prompting speculation that the probe had ceased functioning. As the probe passes further into space, scientists are never sure if each contact attempt will be the last.

Pioneer 10 passed the orbit of Pluto in 1983 and is now, at 12-billion kilometers away, twice as distant. Cosmic radiation counts, detected by the still-functioning Geiger-Tube, will determine when the probe leaves the domain of the Sun and crosses into interstellar space. On a one-way path out of the Solar System, Pioneer 10 (like sister ship Pioneer 11) carries a gold plaque with engraved symbols. This "message in a bottle" is meant to be deciphered by alien beings that encounter the probe. With two-millions years to go before its first stellar encounter, we may develop technologies to reach the stars way before Pioneer does.

More information:

NASA/Ames; Mar. 4, 2002; Press Release: "An Early NASA Pioneer Still On The Job In Deep Space"