November – Gravitational Magnification

At 19:12 on Wednesday 8th of November, the shadow of the planet Mercury fell on Earth and with appropriate equipment you could see its silhouette gradually move across the face of the sun from the lower left to the lower right. Mercury is a tiny planet (and casts a silhouette smaller than a sunspot visible at the time) and moves very slowly, completing its journey just after midnight. Of course we can’t see the Sun at 19:12 from Salford in November, so none of this transit was visible to us. However, the Sun was visible at the

Big Bear Solar Observatory, on the Big Bear Lake in California, and they produced this composite image of the transit as part of their imaginatively named Global Oscillation Network Group (GONG) observations. Clicking the image takes you to their website with further images.

Fifteen minutes after the start of the Mercury transit on the “day side” of the hemisphere, members and visitors of Salford Astronomical Society were taking their seats on the night side for an illuminating presentation from two “local stars”. Kevin Kilburn from Manchester Astronomical Society talking about his latest research into the life and work of James Naysmith, a Scottish Engineer and Astronomer who worked and lived in the western suburb of Salford called Patricroft. That Naysmith lived in a house called Fireside was well documented but no one had to place a X on the map to mark its position. Kevin, with the assistance of the Eccles & District History Society has finally pinpointed the location of Fireside and probably the site used by James Naysmith for the 20 inch telescope, too. The most remarkable discovery was the plan that Naysmith had for a huge 60 inch telescope for nearby Worsley. Had it been built, it would have been the world’s second largest telescope at that time. The picture provided by Dr Norman H Reid (University of St Andrews Library) shows the tiny image of the observer, seated at the pivot point.

Following the electricity reconnection, repair work on the dome recommenced. Although some, mainly cosmetic, work remains, the heavy duty welding on the observatory was completed over six weekends of hard labour by Richard, Jeremy, Jim and Ken.

On 22nd November, Andy Newsom from Liverpool John Moores University eloquently illustrated his research in detecting stars in the halo of Andromeda galaxy and the highly automated technology of robotic telescopes and data processing. A modern astronomer, it seems, rarely puts her eye to an eyepiece, nor is she troubled with the physical requirement of visiting an observatory. Astronomers world-wide lament as astronomy becomes less of a globe trotting adventure than it used to be only a decade ago. The upside is the enormous increase in productivity from data collection, processing and publishing.

They now use the same technology of automation to offer Distance Learning Courses in Astronomy to people who live in Liverpool, Lisbon or Los Angeles.

Andy described how microlensing techniques lead to the discovery of the smallest (to date) extra solar planet in which Liverpool (along with 9 other Universities) had participated. Microlensing, an effect predicted by Albert Einstein in 1912, is a technique employed by radio - not optical - astronomers. But if you could see it it would look something like the following.

On the evening of July 3rd 1989 Titan, the largest moon of Saturn occulted a distant 5.4 magnitude star in the constellation of Sagittarius (28 Sgr). A very short video (frame size=160 by 120, duration 10 sec, size= 757KB) version of the observation made by Ken Irving of Salford Astronomical Society shows Titan obscuring 28 Sgr at 4.09 on the foreground clock, Titan’s atmosphere (the only moon in the solar system which has one) acts a magnifying glass, temporarily brightening the “still obscured” star. Ken’s observations along with many others helped NASA to plan the 2004 Cassini-Huygens probe to explore Titan and its atmosphere.

Although radio astronomers don’t work with light, habits die hard and they still use the term “light curve” and the light curve of a microlensing event from July/August 2005 illustrates the discovery of the extrasolar planet. The diagram represents observations over two months from multiple observatories. The main peak represents the temporary brightening of the distant star as the gravitational force of the unseen foreground star plays the role of a magnifying glass. The minor peak at about 15th August (a larger version "planetary deviation" in the top right hand corner) is the tell-tale sign of the orbiting planet. It is equivalent to the 28 Sgr brightening event on the video but that of course was result of atmospheric refraction, not microlensing. A more technical description is provided online at LJM’s Angstrom project. here.

During Christmas 2003 you, like me, may have followed the Beagle 2 mission via the Yahoo Group which is no longer active following the premature demise on landing. The Yahoo Group was established and managed by Doug Ellison who now runs the popular and well respected www.unmannedflight.com. Doug gave a talk at the Manchester University’s “Students for the Exploration and Development of Space”, MANSEDs. You don’t have to be a student nor young to attend - anyone can.

Doug has been studiously following the Mars Rovers since their landing and has a wealth of knowledge about their exceptional achievements. He had brought along some incredible pictures from the surface of Mars. This one above, for example, shows Opportunity observing its own heat shield which it discarded during entry and the impact it made on the surface of Mars. The two NASA rovers designed for 90 days, are still operating after and incredible 700 days!

A picture from the orbiting NASA's Mars Reconnaissance Orbiter shows Opportunity and its tracks in the Martian sand.