Volume 14 • Issue 2 February 2015 ISSN 1712-4425 peterboroughastronomy.com twitter.com/PtbAstronomical The Reflector Newsletter of the Peterborough Astronomical Association Minor mergers have massive consequences for black holes Images credit: NGC 3393 in the optical (L) by M. Malkan (UCLA), HST, NASA (L); NGC 3393 in the X-ray and optical (R), composite by NASA / CXC / SAO / G. Fabbiano et al. (X-ray) and NASA/STScI (optical). DR. ETHAN SEIGEL hen you think of our of our sun or smaller, a rare but the Milky Way, houses a supermas- sun, the nearest star to significant fraction are ultra-mas- sive black hole that weighs in at Wour world, you think of sive, containing tens or even hun- about four million solar masses, an isolated entity, with more than dreds of times the mass our star while our big sister, Andromeda, four light years separating it from contains. When these stars run out has one nearly twenty times as its next nearest neighbor. But it of fuel in their cores, they explode massive. But even relatively iso- wasn’t always so: billions of years in a fantastic Type II supernova, lated galaxies didn’t simply form ago, when our sun was first creat- where the star’s core collapses. In from the monolithic collapse of an ed, it very likely formed in concert the most massive cases, this forms isolated clump of matter, but by hi- with thousands of other stars, a black hole. erarchical mergers of smaller gal- when a giant molecular cloud con- Over time, many generations axies over tremendous timescales. taining perhaps a million times the of stars — and hence, many black If galaxies with large amounts of mass of our solar system collapsed. holes — form, with the majority stars all have black holes at their While the vast majority of stars eventually migrating towards the centers, then we should be able to that the universe forms — some centres of their host galaxies and see some fraction of Milky Way- ninety-five percent — are the mass merging together. Our own galaxy, see “Chandra” on page 16 2 • peterboroughastronomy.com President’s Message Executive Meeting Results our executive met in January to ing “Bring your telescopes for a night of ob- discuss and act on a number of busi- serving” following a brief meeting indoors. ness related issues for the paa. A Ken Sunderland proposed the acquisi- Ysynopsis of the discussion is here. tion of lanyards to replace the strings used We plan to have “The President’s bbq” on on our badges. More on this at the February Saturday June 20th at the Robinson Road Meeting. Observatory. Details will follow in the com- There was discussion about the flow of ing weeks. information with ideas like Facebook tossed The website has been moved, Boyd will around. No decision made. fill us in at the February meeting. Rodger Forsyth The theme for the Library Display this PAA President year will be “Our Changing Solar System.” The date for the April meeting will be the 10th at Fairview Church with the focus be- Letter from the Editor Commenting on Comets e have something almost like a Our contributors were so productive last theme this month: comets. Yes, month that I’ve had to hold back some of W we have lots of photos of Comet their submissions for next month and be- Lovejoy C/2014 Q2. Brian McGaffney and yond. So come back next time and we’ll see John Chumak took some fine photos of this what else our writers have penned for you. faintly visible dirty snowball in the sky. John Phillip Chee Crossen describes Brian’s photo in a short Editor, The Reflector article but also begins a much longer three- part series on the Rosetta mission, that, you guessed it, landed on a comet. Comet 67P to be precise and John is not lost for words as he also has an article on 67P itself. Rick Stankiewicz has been back from China awhile and has his second China The Reflector Travel Tour article, this time about the Great Wall of China. While back in Canada The Reflector is a publication of the Peterborough Astronomi- he also tried to observe last month’s triple cal Association (P.A.A.) Founded in 1970, the P.A.A. is your local group for astronomy in Peterborough and the Kawarthas. transit across Jupiter’s surface. Read on to www.peterboroughastronomy.com • [email protected] see how he fared. Phone: 705.292.0729 Club Mailing Address Ken Sunderland returns with another Rodger Forsyth, President Peterborough Astronomical Association book review, this one concerning Lee 536 Robinson Road RR #1 Billngs’s Five Billion Years of Solitude. Peterborough, ON K9J 6X2 Vol 14 • Issue no. 2 • February 2015 • 3 The Reflector The Rosetta Mission — Part 1 Catch a Comet by the Tail JOHN CROSSEN he rosetta mission has seen Comet Halley. A number of countries sent more ups, downs and plot swaps probes to analyse the comet’s tail materials. than a bad murder mystery. For A few years later esa’s Giotto Probe of yet Tstarters the comet to catch was Comet another comet brought new knowledge of 47P Wirtanen. But launch delays caused the origin and composition of these cosmic scientists to switch targets to Comet 67P/ interlopers. The Giotto Probe also inspired Churyumov–Gerasimenko. For sanity’s interest in future missions to these messen- sake, let’s just refer to this snowball from gers from the outskirts of our solar system. outer space as Comet 67P. As originally proposed in the late 1980s, Unless you’ve spent the last 2 months the mission was to be a duet staring nasa watching the and the Sleep Network, European you know that Space Agen- the mission to cy — esa. reach Comet 67P The nasa was successful. version was What you prob- a simple fly- ably don’t know by mission is the intriguing called craf trail of events for Comet that unravelled Rendezvous during the Ro- Asteroid Fly- setta Mission’s by. The esa decade-long version was a trek. more ambi- The mission tious mission takes its name calling for the from the Rosetta spacecraft Stone which to land on a was the key that comet and re- unlocked the turn samples translation and to Earth for understanding examination. of hieroglyphics. To minimize The similarity expenses the here is that land- two agen- ing on Comet ARIANE ROSETTA ROCKET LAUNCH. From its inception in 1984 the Rosetta cies would 67P will help Mission has overcome a myriad of near-fatal challenges. Pictured here is share design the Rosetta Mission aboard an Ariane 5 rocket as it finally launched from us understand French Guiana. Photo was taken by the Blue Planet Chanel. knowledge as more about how well as rock- our solar system formed. It will be our new etry. Rosetta Stone revealing the 4.5-billion-year- However nasa’s funding was drastically old secrets of our origins. cut, leaving esa to shoulder the whole load. The seeds of the Rosetta Mission were It also caused esa to do a lot of rethinking planted in 1984 during the close approach of See “Rosetta” on page 15 4 • peterboroughastronomy.com Can you see the Great Wall of China from the Moon? RICK STANKIEWICZ hat do you think? Let’s start height of 7.6 m (25’). The length of the Wall by explaining what the Great is also punctuated with watchtowers at ir- Wall is, before discussing what regular intervals. Through its connection to Wit isn’t. folklore, it is easy to see how the Great Wall The Great Wall of China (in Chinese might follow the track of a dragon up and means Long Wall) is a series of long forti- down the spiny ridges of the rugged terrain fications made of stone, brick, compacted it has now become part of. From what I saw earth, wood, and natural barriers, basically of this longest fortification structure in the along an east-to-west line across the histor- world, it is indeed an impressive sight. ical northern border of China and southern On my recent trip to China in the fall of border of Inner Mongolia. This was done 2014, I was fortunate to have had the oppor- in part to protect the Chinese Empire or tunity to walk on the Great Wall on a cool its states, against various military incur- sunny morning in November (see attached sions by warlike peoples (Mongols). The images). Declared a unesco World Heri- Great Wall construction was started be- tage Site in 1987 the Great Wall receives a tween 220–206 BC by the first Emperor of large daily dose of visitors and tens of mil- China, Qin Shi Huang (Qin — pronounced lions annually. “chin” — Dynasty). However, most of the Since as early as 1754 there has been a Great Wall seen today is from the Ming space-based urban myth about the Great Dynasty (1368-1644 ad). The length of the Wall of China being the only manmade Great Wall with all its various branches and structure you can see from the Moon. In segments (not a continuous structure) mea- 1932, Ripley’s Believe it or Not cemented this sures over 21,000 km (13,000+ mi). The Wall myth in our pop culture. Given my view averages a width of 9 m (30’) at the base and of the Great Wall as I flew from Beijing to 4.6m (15’) across the top, with an average continued on next page Vol 14 • Issue no.