Sky Wise

Buying a Telescope?

Photo:  XT10 Dobsonian Telescope by Orion

You would think that buying a telescope would be a no-brainer, wouldn't you?  Go to the local store, pick out one that says it has monster-size magnification and whisk it over to the checkout counter.

Christmas time is upon us and thousands of telescopes will be purchased in just such a manner.  Unfortunately it usually results in a poor choice -one that doesn't do a good job.  Most find homes in the bottoms of bedroom closets.  You see, much of the telescope stuff out there just isn't very good -especially the cheaper stuff.

Want to know how to find a good telescope for a beginner?  Here's a quick guide to navigating the choices.

My first recommendation isn't actually in purchasing a telescope.  A decent pair of binoculars is the first step, along with a sky chart or planisphere.  For a modest price, you can be up and running.  If the interest in astronomy doesn't last, you still have a decent set of binoculars.

Still want a telescope to search the heavens?  Okay, take a deep breath first.  Here goes....

You want a telescope that doesn't look like a telescope.  It looks like a big sonotube they use for pouring concrete footings.  Next, they've put it on a lazy-susan.  Yes, I'm not kidding you.  This type of astronomical telescope gives you the best bang for the buck.  It's easier to use, gives decent views and astronomers will thank you for giving junior the right equipment.  This type of telescope is called a "Dobsonian" reflector.  They are the perfect beginner telescopes because your money is going into a stable base and very good optics.  No extra doodads or gazidlywinkers means that you are actually buying a decent piece of equipment. 

Do you need anything else?  Yes.  A map of the sky.  I'll tell you a secret.  Astronomers tend to ignore individual stars because they look the same in the telescope.  What they are really looking for is weird things like galaxies, nebulae, comets etc.  You can't find them without the proper road map.  When you go to the astronomy store for that telescope, pick up a decent star chart or even an astronomy magazine like "Sky News" which has a star chart inside.  Another great idea is a star chart and planetarium program like "Starry Night".  I use this software in my blog to give you those pretty maps you see all the time.  Not sure where to buy a telescope?  Canadians have great resources available to them to order on-line.  "Astro Buy & Sell" is a popular starting point.  This website contains both astronomy dealer ads and astronomy classified ads.  Finally, consider a membership in a local astronomy club.  I've been a member of the Durham Region Astronomical Association since 2001 and have learned more through talking with other astronomers than I ever would with books. 

I know you still want the one in the department store -the one that says "675 POWER".  Resist.  It's big on promises but big on frustration.  It will be used once, on the moon and then never again because it is impossible to point.

Good luck and happy shopping!

A Break in the Clouds

Image created in Starry Night Pro, copyright IMAGINOVA

I'm overjoyed that a window of opportunity has opened up for you to see winter's constellations starting to rise in the east.  All this week the forecast is looking good and at last I can take out my 10 inch dobsonian reflector -a Newtonian on a lazy-susan type base. 

Look in the east around 9:30 PM this week and you will see the constellation Orion, our mighty hunter rising up out of the trees -or if you live in town, the buildings.  Orion's belt of three bright stars are visible as a remarkably straight line, about the distance across of two fingers held together at arm's length.  Hanging off of Orion's belt is a faint fuzzy star.  Look at it through binoculars or a telescope to see it as it really is -a big, beautiful nebula!  I described the Orion Nebula in a previous entry.  Just scroll down for more details!

Orion is the home of two other prominent stars that are quite easy to see.  His right shoulder -on the left as we look at him- is the red supergiant star named "Betelgeuse".  This behemoth is so large, if we were to place it where our sun is, the Earth would be orbiting inside it.  It's 667 times the size of our sun. You can see easily this star's reddish colour when you view it.

His left knee is another bright star named Rigel.  This is another giant, about 92 times the size of our sun.  Rigel has a small companion star but it's too difficult to see it in Rigel's glare without very advanced equipment.  Rigel burns a bright blue-white light vs. Betelgeuse's orangey-red.

Beside Orion, you can see the constellation Gemini, the twins.  Castor and Pollux are the two bright stars you can see on the left.  Each of these stars is also a double star!

More winter treasures await us!  I hope you will join me.

Are you interested in learning more about astronomy, stargazing and the wonders of the night sky?  Consider attending the next meeting of the Durham Region Astronomical Association.  It's FREE to everyone and a great way to meet other people who share your interest in astronomy.  The next meeting is on Tuesday, November 21st at 7 PM.  Meeting location is 66 Simcoe Street South in Oshawa.  For more information please visit the website of the DRAA  .

The Weather Gods must be Angry

Picture Credit:  SOHO (ESA, NASA)

It's getting depressing for those of us who like to see stars in our night skies.  The weather here in southern Ontario just hasn't been up to snuff since August.  This has required a switch in my habits.  My astronomy fix now requires sitting at the computer and seeing what's out there.

Lucky for me there are a number of interesting websites which keep me entertained.  One such site is SOHO

This picture is from the Solar and Heliospheric Observatory, also known as "SOHO".  SOHO is actually a space-based telescope floating out there in the abyss, at a point far out from Earth.  It has special cameras which have been optimized to study the sun's output at specific wavelengths of light.  This picture was taken in the wavelength of 304 Angstroms.  The bright area is about 60,000 to 80,000 degrees Kelvin.  That being said, there's another picture at 284 Angstroms which shows the same area shining brightly at 2 million degrees. 

This bright area corresponds with a sunspot, a storm on the sun where the magnetic fields twist and turn and cause a welling of plasma at the surface.  These solar storms sometimes give rise to solar flares.

Here's a SOHO picture of the sun through a wider spectrum of light.  In this image the sunspot appears dark (hence the name).  I haven't measured it but this sunspot has to be at least five times the size of the Earth (you can line up 109 Earths across the sun's face).

Nice to know that the sun's still shining despite our clouds and rain.

Maybe we'll have clear skies again soon -sigh!

A Rare Event

Picture:  Fred Espenak, NASA

On November 8th, we will witness a rare event.  The planet Mercury will cross in front of the sun.  You would think that this should happen all the time since Mercury is orbiting the sun just like we are -but it's more complicated than that.  Mercury's orbit is on a slightly different plane than Earth's and most of the time it passes above or below the sun's disk.  For an actual pass in front of the sun -known as a transit- our orbits have to be aligned just right.

After the transit of November 8th, you have to wait until the year 2016 to see it happen again.  The good news is that you can safely witness the November 8th transit personally.  Special solar filters which fit over the front of your telescope are available from astronomy retailers.  If you don't have this option, you can also attend viewings in various locations.  Night Sky Tours in the Durham Region will be providing opportunities for people in the GTA to see the Mercury Transit from a location in Oshawa.  I'm sure there are other groups doing this too. 

Please note that you MUST have special solar astronomy equipment to see this safely.  Do not look at the sun without astronomical grade solar filters.  Blindness can and will result without doing this properly.