Why Can’t we see the Oort Cloud?

Hubble Space Telescope observation of Polaris – looking through the Oort Cloud, but not resolving any comets (Hubble)

The Oort Cloud is a mysterious entity. Located on the outskirts of the Solar System, this hypothetical region is probably the source of the long-period comets that occasionally pass through the inner planets’ orbits. The strange thing about these comets is that they have orbits inclined at pretty much any angle from the ecliptic which suggests their source isn’t a belt confined to the ecliptic plane (like the asteroid belt or Kuiper belt). Therefore, their proposed source is a cloud, acting like a shell, surrounding the Solar System.

OK, so we think the Oort Cloud is out there, and there is a lot of evidence supporting this, but why can’t we see the Oort Cloud objects? After all, the Hubble Space Telescope routinely images deep space objects like stars, galaxies and clusters, why can’t we use it to see embryonic comets within our own stellar neighbourhood?
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No, An Alien Radio Signal Has Not Been Detected

Schematic showing Sagittarius A crossing the beam of Indlebe on 28 July 2008 (Stuart MacPherson)
Schematic showing Sagittarius A crossing the beam of Indlebe on 28 July 2008 (Stuart MacPherson)

Some great news from Durban University of Technology in South Africa, their newly built Indlebe Radio Telescope detected its first signal late last month. “On the evening of 28th July 2008, at 21h14 local time the Indlebe Radio Telescope, situated on the Steve Biko campus of the Durban University of Technology (DUT), successfully detected its first radio source from beyond the solar system. A strong source was detected from Sagittarius A, the centre of the Milky Way Galaxy, approximately 30 thousand light years away,” says the statement by Stuart MacPherson. This will be an invaluable resource for students and research projects; a great achievement.

Although this should be the focus of attention, it looks like social bookmarking may have struck again. The DUT announcement was picked up by Digg and the Internet population drew their own conclusions. Interestingly, the Russian mainstream media was listening and interpreted the Internet buzz as proof that an alien radio signal had been detected in the centre of our galaxy…
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Meteor Alert: Perseid Shower Now Active (Update)

The 2004 Perseid meteor shower (© Fred Bruenjes)
The 2004 Perseid meteor shower (© Fred Bruenjes)

Update (1:30am PST): Spotted three very bright and several dim meteors in a 10 minute observation period (not bad for LA skies!). The bright meteors left strong, and long-lasting ionization trails that were visible for a couple of seconds. It can only get more active, so I’ll be back outside soon…

OK, so for my second attempt at seeing the Perseid meteor shower, I’m donning the shorts and T-shirt (not your usual astronomy garb, but this is California!) and getting out into the back yard. I’ll be looking North-East, through a clearing in the palm trees and keeping an eye open for the Perseus constellation. As you can probably tell, I’m no practical astronomer, but my wonderful colleague Tammy Plotner’s enthusiastic writing is infectious and I want to catch some shooting stars with my own eyes!

Wish me luck…
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Observing Red Dwarf Stars May Reveal Habitable “Super-Earths” Sooner

A planet orbiting a red dwarf (NASA)

OK, so if you’re an exoplanet hunter, which stars would you focus your attention on? Would you look at bright blue young stars? Or would you look at dim, long-lived red stars? If you think about it, trying to see a small exoplanet eclipse (or transit) a very bright star would be very hard, the luminosity would overwhelm any attempt at seeing a tiny planet pass in front of the star. On the other hand, observing a planet transiting a dimmer stellar object, like a red dwarf star, any transit of even the smallest planet will create a substantial decrease in luminosity. What’s more, ground-based observatories can do the work rather than depending on expensive space-based telescopes…
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