Wednesday, July 27, 2011

Canadian Astronomers Discover Earth's First Companion Asteroid

We're all familiar with Earth's large companion, better known as the Moon. Well it turns out that our planet has another, albeit much smaller, companion that has just been discovered by Canadian astronomers.

The companion is an asteroid, named 2010 TK7, and is about 300 metres across. Among the many thousands of asteroids known, most are simply orbiting the sun in a band between the orbits of Mars and Jupiter. However, there is a special class named Trojan asteroids because they orbit around one of the two Lagrangian points which lie 60° ahead of and behind the larger body. in its orbit. Jupiter has a large number of Trojan asteroids, possible as many as exist in the main asteroid belt.

So while Trojans have been associated with Jupiter, Saturn, Neptune and even Mars, none had been known to be associated with the Earth.  Astronomers had predicted Earth should have Trojans, but they have been difficult to find because they are relatively small and appear near the Sun from Earth's point of view.

2010 TK7 was initialized discovered by the WISE orbiting infrared telescope which afforded astronomers a different perspective that they usually get from Earth-bound telescopes. Once this object was identified as an interesting candidate, followup observations with Canada-France-Hawaii telescope on Mauna Kea confirmed that 2010 TK7 was indeed the first Earth Trojan.

There are likely to be many more Earth Trojans and now that the first one has been identified the race will be on to discover more.

Tuesday, March 29, 2011

Canadian Universities Join New Telescope Consortium

Canada is a world leader in astrophysical research and much of this leadership depends on access to forefront, world-class telescopes. Astronomer's push to understand the Universe depends on building ever more powerful, and specialized, telescopes. This push has seen telescopes grow from Galileo's 2.5 cm (0.025 m) specimen to the proposed Thirty Meter Telescope (TMT).

One other significant change from Galileo's day is that astronomer's now use telescopes that span most of the electromagnetic (EM) spectrum from gamma rays to long wavelength radio waves. Each part of  the EM spectrum offers a different perspective on the Universe and the ability to investigate different processes.

The new proposed telescope that seven Canadian universities have joined is the Cerro Chajnantor Atacama Telescope (CCAT) which will be located high in the Atacama desert in northern Chile. CCAT will be the world's largest telescope viewing the Universe in sub-millimeter radio waves. This type of telescope is extremely useful for studying galaxies in the very young Universe. This was a very active time for galaxy and star formation.

The telescope was located in Chile for two very important reasons. The first is that the site is ideal for this type of telescope, It is "high and dry" which means that the observations will not be hampered by the atmosphere. The second reason is that the soon to be completed ALMA telescope will be located very near by and these two telescopes will complement each other extremely well. ALMA works in the same part of the EM spectrum and will be able to study the galaxies discovered by CCAT in exquisite detail.

More information

Monday, March 28, 2011

100 Years of Variable Star Observing

This year, 2011, marks the 100th anniversary of the American Association of Variable Star Observers (AAVSO). Despite its name, the AAVSO is a truly international organization, with members in just about every country. It's a fantastic example of collaboration between professional, semi-professional, and amateur astronomers.

The focus of the AAVSO is variable stars--a type of star whose brightness varies over time, usually in a cyclic pattern. Variable stars play an extremely important role in astronomy. Certain types of variable stars obey an interesting relationship, whereby the time it takes for them to complete a cycle of brightness changes--from dim, to bright, and back to dim again--is related to the amount of light they are emitting on average. This means that, if we can measure how long it takes a variable star to go through a brightness cycle, we can work out how bright the star is intrinsically. Knowing how bright the star is intrinsically, we can work out how far away it must be to appear as bright as it does to observers on Earth. Variable stars are often the only means we have to determine the distances to celestial objects.

Many variable stars are easily visible from Earth with a small telescope. A few are even visible to the naked eye. They are popular targets for amateur astronomers. Every year, the AAVSO collects more than half a million observations of variable stars from amateur astronomers around the world. They catalog these observations and make them available to everyone. Many of their results have been used by professional astronomers in scientific publications. Canadian astronomers are among the AAVSO's strongest supporters. John Percy, past president of the AAVSO and Professor Emeritus at the University of Toronto, has relied on AAVSO data for years and has been instrumental in encouraging participation in AAVSO activities.

This year, the AAVSO is celebrating 100 years of "citizen science". Among the celebratory activities is a challenge to observers the world over to observe 100 variable stars in 100 days. Some eager Canadians have already completed the challenge. Why not try to observe a few variable stars yourself? The AAVSO publishes a handy guide to help you get started.

Monday, March 21, 2011

Strange New Worlds

University of Toronto astronomy professor Ray Jayawardhana's first popular science book, Strange New Worlds: The Search for Alien Planets and Life Beyond Our Solar System is now in wide release. It's in its second week on the Canadian non-fiction best-seller list, according to Maclean's. Congratulations, Ray!

Ray's book describes some of the first concrete steps taken by astronomers to answer the age-old question, "Are we alone?" Canada enjoys a significant concentration of researchers who study exoplanets, which are planets orbiting stars other than the Sun. Although the study of solar systems other than our own has yet to turn up an alien civilization, recent results indicate that Earth-like planets are probably not extremely rare. They may even be common!

Interested in learning more about the search for exoplanets? Why not pick up a copy of Ray's book, or head to one of the many talks he'll be giving in libraries and other public places around Canada and the US over the next few months?