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| Despite the controversy over the SHGb02+14a, it is still an interesting signal. So the search continues. | Despite the controversy over the SHGb02+14a, it is still an interesting signal. So the search continues. | ||
| ==External links== | ==External links== | ||
Revision as of 17:46, 26 April 2005
The correct title of this article is Radio source SHGb02+14a. It appears incorrectly here due to technical restrictions.SHGb02+14a is an interesting radio source and candidate in the Search for Extra-Terrestrial Intelligence discovered on March 2003 by SETI@home and announced in New Scientist on September 1, 2004. This weak source was observed three times at 1420 megahertz and emitted from between the constellations Pisces and Aries. According to the New Scientist, the 1420 MHz frequency would be one that extraterrestrials would use, since it is one of the main frequencies at which hydrogen, readily absorbs and radiates energy.
There has been more skepticism than a welcoming to the event. Most researchers dismissed the signal as an artifact of random chance, cosmic noise or maybe just a glitch in the technology.
Another reason for the skepticism is that there is no star within 1000 light years of that direction.
Some of the most explicit arguements expressing skepticism for the signal was done by an article from the blog The Blogging of the President:2004. It argues that "Hydrogen is just a proton with an electron in its orbit; both the proton and the electron have a magnetic dipole moment. There is a tiny energy difference between alignment and anti-alignment, and when the system flips, you get a tiny photon at 1420 MHz (a wavelength of 21 cm, hence the 21 cm line). There's a lot of neutral Hydrogen in the galaxy and therefore there is a lot of radiation at 1420 MHz. It was one of the first detections made when we invented radio astronomy."
The article adds that, "there are some more oddities to the signal. In the three times it has been detected, it has doppler shifted quite rapidly. This is presumably due to the motion of the source itself relative to us. A shift of 37 Hz per second (the maximum observed) would mean that the source was accelerating at around 8 meters/second^2. If the civilization was sending out a signal from a home planet in orbit around the Sun, this would imply a pretty rapid rate of rotation. The Earth's acceleration about the Sun is much less."
In the same article, the blog argues that, "nother oddity about this signal is that it lasts around a minute or so. This implies that the region that it came from was less than a light-minute in size. This is very unusual, since the 21 cm line emission is usually very faint, and requires a large amount of material spread out over much larger scales. I don't know the amplitude of the signal, but from what I understand, one light-minute (less than the size of the Earth's radius of orbit) is a fantastically tiny region to get a significant amount of 21 cm emission from. More indeed, the fact that signals never lasted longer than a minute which makes it difficult to analize them."
A more skeptical article concerning the discovery was written by The Planetary Society.
Despite the controversy over the SHGb02+14a, it is still an interesting signal. So the search continues.
External links
- New Scientist article
- Article on the Planetary Society's website
- SETI Project signal candidate page
- SETI range calculator