Star Hopping

Today I want to remind you of what we did at our first class, star hopping.  If you create a path in the sky from one constellation to the next, it’s a lot easier to learn all of the stars and constellations.  Let’s start in the North with Ursa Major.  You should be able to find it by now as soon as you look into the northern sky.  Once you find the bear,  pick out the part of the bear that looks like a big dipper.  The two stars at the front of the dipper are Dubhe on the left and Merak on the right.  Draw an imaginary line through the two stars heading north.  After you’ve gone 5X the distance between Dubhe and Merak you should run into a star that will be due North.  That’s Polaris or the North Star.  Hanging off the North Star will be another dipper, smaller than the first one and that’s Ursa Minor or the Little Dipper.

Extend the line from Ursa Major to the North Star that same distance and you should find a big W or M.  That’s Cassiopeia, the queen of the night sky.  It actually looks a little like a chair or throne.  Once you imagine the queen, look where she’s looking and you should see a large group of stars that look like a house.  That’s the head and crown of the Cephus the King, who actually looks a lot like a block headed clown.  Now you’ve found all of the easy constellations in the Northern sky.

Turn around and face South.  The first thing you should see will be the three stars that make up the belt of Orion the Hunter.  Above the belt are two very bright stars that look like they could be shoulders.  Betelgeuse is on the left and Bellatrix is on the right.  Above the shoulders are three rather faint stars right where Orion’s head should be.  Below the belt are three bright stars that could be a sword and below those are two more very bright stars that would be his legs.  Saiph is on the left and Rigel is on the right.

Imagine a line through Orion’s belt heading West and follow it until you run into a letter V, that’s the face of Taurus the Bull. Look up to where the bull’s horn should end and you’ll find a big pentagon of stars, that’s Auriga the Herdsman.  He doesn’t look much like a shepherd, but if you find the brightest of the five stars, imagine that’s his goat with her three babies nearby.  She’s a singing goat, but she doesn’t have a band so she sings “a cappella” and what is her name? Cappella.

If you were drawing a circle in the sky from Orion to Taurus to Auriga and kept going you would run into two very bright stars that look almost alike.  That’s the twin brothers Pollux and Castor.  The stick figures of their bodies are right between the brother stars and Auriga.  Remember what the boys are doing?  Walking the dogs.  Follow Pollux’s arm to two more stars, one bright, one dim.  That’s the little dog, Canis Minor and the brighter star is Procyon. If you have a little dog keep going down toward the horizon until you run into a very bright star, Sirius the Dog Star which is the eye of Canis Major.  Want to make sure you’re in the right constellation, look at Orion’s belt and go the opposite way you went to find Taurus.

To find the next few constellations, look back up at Ursa Major.  Follow the arc of the bear’s tail until you run into another bright star, Arcturus.  Remember arc to Arcturus.  That’s the star at the bottom of another shepherd Bootes, but I like to think of it as Bootes the Kite with the four stars that make up the long and short pieces of a kite.  Keep on going past Arcturus until you run into another very bright star, Spica.  So if you arc to Arcturus you can just speed on to Spica.  Spica is a the end of the tail of a great big letter Y that will be rising up into the South.

Back to Ursa Major and Dubhe and Merak.  Follow them the opposite way that you went to find the North Star and you’ll run into a great big backwards question mark.  Nearby it to the East is a triangle and when you put the two figures together it looks just like a lion, Leo the Lion.  Right in front of the lion’s head will be Jupiter, the brightest dot in the sky and Jupiter is sitting right in the middle of the constellation Cancer.  If you’re wondering if you’re in the right place, Cancer is right between Leo and the Gemini.

If you can work you way through all of those steps, you’ve found more than enough constellations and stars to pass requirement 4 a & b.  Practice doing this for the rest of the week on clear nights and you should have no trouble Saturday.

Mike

http://www.Mike-Francis.com/sst.htm

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Planetarium on your computer

One of the hardest parts of the Astronomy Merit Badge is identifying at least ten constellations (requirement 4), four of them in the zodiac, and eight conspicuous stars. Here is a list of most prominent constellations and stars, which are visible in the night sky now. This is the list you should try to learn to identify for the test.

Constellations:

  • Ursa Major
  • Ursa Minor
  • Cassiopia
  • Cephus
  • Draco
  • Orion
  • Taurus
  • Auriga
  • Gemini
  • Canus Major
  • Canus Minor
  • Cancer
  • Leo

Stars

  • Dubhe
  • Merak
  • Polaris
  • Sirius
  • Betelgeuse
  • Bellatrix
  • Rigel
  • Saiph
  • Aldeberan
  • Capella
  • Castor
  • Pollux
  • Procyon
  • Regulus
  • Arcturus
  • Spica

You don’t have to learn all of them (see the book), but if you know all of them it will make it easier to take the test. One way to learn them is by using a computer planetarium program. One of my favorite free programs is Stellarium. It’s available in Windows, Mac and Linux versions so download it (with your parents permission of course) and play around with it for a while, to get a hang of how it works.

Stellarium a desktop planetarium

If you’re using another program adjust what you do to the program you’re using.

First thing is to set your location. If you’re using Stellarium there will be a little tool bar on the lower left side of your screen and one of the tools is a little wrench. Click on it to open the set up box. Click on the location tab and you will find several options, but the ones we’re interested in are latitude and longitude.

Do you know yours? If you don’t you can go here to find it: http://www.zipinfo.com/search/zipcode.htm . To check latitude and longitude just enter your zip code. This will be your local post office as your observation point which is close enough for us. Enter your coordinates by using the little up and down arrows next to lat. and long. in Stellarium and click save, so you always start out looking at the sky the way it will in your back yard.

Now click on the Date & Time tab and check to make sure the current date and time are set. If they are incorrect, your computer may have the wrong date set so check your computer’s clock. If you want to play with the landscapes, go for it, but Guerens (the skyline you get when you first start the program) seems to be the best choice for keeping the screen fairly clean and still give us a reference for where the horizon is. Close the set up screen and now we can take a look at the sky.

If it is already night time you’re all set, if it’s day time you need to speed time up a little. Click the fast forward (>>) on the lower right of the screen two or three times. Don’t get carried away or time will really fly. When the sky gets dark hit the play (>) and time will slow down to real time. Now you should see a nice clear night sky and a few stars. If you have a scrolling mouse, try scrolling your view in and out. If you don’t have a scrolling mouse use the page up and page down keys. Too much ground, too few stars? Left click anywhere on the screen and drag your view up or down. You can also drag left and right to look to the East, West, North or South. Play around with this for a while until you get used to it.

If you can find Mars ( it will be low in the West at around 8:00 pm ), click on it and hit your space bar. What happens? Now try scrolling or using the page up and down keys. You can do this with any objects that could be seen with a telescope, I’ll give you some things to look for on another day.

Now to start learning the constellations and star names.  Try playing with the three controls on the left end of the control bar. By turning these on and off and learning the star patterns behind the graphics, you should be able to start learning the constellations.

If you are using another desktop planetarium and having trouble, you can email me with your questions as I have several other programs and I should be able to help out. When it’s clear at night go out right after sunset and see if you can apply what you’ve learned.

If you have any problems or questions, send them along.

Mike