Starship 101

At Orbit!, the 3D online planetarium, you can fly in orbit around the Earth, view the stars, travel in time, find the planets, see what Earth looks like from the Moon, see the far side of the moon and much more.  You can see constellations, dial in specific star coordinates and see the sky divided into constellation boundaries.  The milky was is available in two optical intensities as well as infrared and atomic hydrogen.

What even more incredible is that this online planetarium is celebrating it’s 10 year anniversary this summer.  It’s hard to believe that cyber technology this good has been around for over a decade.

Star maps or star charts help us to find things in the sky.  They are not the 3D-charts that would help starship captains to find a planet to land on, but they would point them in the right direction when they first leave Earth.  They are a projection of celestial objects on a virtual sphere that our planet is inside of.

These maps break-up the sky into areas, similar to states or providences in a country that correspond to constellations.  Stars within these areas are given names based on the Latin name for the constellation proceeded by a Greek letter.  For example, Rigel is Beta Orionis (Orion), the north star Polaris is Alpha Ursae Minoris (Little Dipper) and Sirius the brightest star in the sky is Alpha Canis Majoris (Canis Major or the big dog).

To be even more precise there is a coordinate system similar to latitude and longitude.  Right ascension, or Ra, is like longitude except the zero point is not the Prime Meridian, it is the Point of Aries, or where the sun is on the first day of spring.  Ra is measured in hours going east of the Point of Aries.  Declination, or dec, is like latitude, only in the sky.  If you were on the equator and looked straight up, you would be looking at a declination of 0°.  Straight up from the north pole is 90° and straight up from the south pole is -90°.

Sirius is at 06h 45m, -16°, Polaris is at 02h 32m, 89° (pretty close to 90° that’s why it’s called the North Star) and Rigel is at 05h 15m, -8° (close to the equator, which is why Orion can be seen in both the northern and southern hemispheres).

Stephen Hawking would probably say, “Scintillate, scintillate stellar body with a magnitude greater than one.”  But, that would make for a lousy poem.

What makes stars twinkle? Twinkling is technically known as stellar scintillation.  It is caused by atmospheric turbulence.  One of the advantages the Hubble telescope has is not having to deal with twinkling, since it is outside of our atmosphere.

What makes stars little? How big or little a star looks in the sky is a factor of not only how big and bright a star really is, but also how far away it is.  Astronomers measure the apparent brightness of stars using magnitudes.  Unfortunately the scale is backwards.  The smaller the magnitude, the brighter the star.  (Go figure.)

The brightest stars are about -1.  Stars can have magnitudes of -1, 0, 1, 2, 3, 4, and so on.  The scale is logarithmic, kind of like the decibels your stereo puts out.  Each star magnitude is 2.512 times brighter than the previous magnitude as you move down the scale.  A magnitude of 1 for example would be 100 times brighter than a 6. A -1 would be 100 million times brighter than a 19.

There has been a lot of talk over the last few years about looking for water on the moon.  Some feel that there could be a frozen lake in one of the polar craters that has never seen the light of day.  What is the big deal?  Do the astronauts want to go ice skating?

Hardly.  The main reason is that water can be turned into fuel.  Most of the cost of sending things into deep space is fuel.  It costs tens of thousands of dollars per pound to launch a rocket and most of the weight is fuel.  If a rocket could refuel on the moon, it would make deep space exploration less expensive.

Orion the Hunter is a familiar winter friend.  When I lived in South America for two years, this was the one constellation I could see that I recognized from the northern hemisphere.

Orion has two very famous stars, Betelgeuse (right shoulder) a giant red star and Rigel (left knee) a huge blue-white star.  The lesser known Bellatrix (left shoulder) is a name made famous thanks to the Harry Potter books.  The Orion Nebula can be found in the middle of Orion’s sword.

According to mythology, Orion was a giant hunter who challenged the gods by claiming to be able to kill every wild beast in the world.  They sent a giant scorpion that killed him.  After his death, the gods raised both of them to the heavens as constellations.

A light year is the distance light travels in a year, or about 6 trillion miles.  The space shuttle traveling at top speed (17,000 mph) would take about 40,000 years to travel one light year.  To put things in perspective, the closest star is 4.3 light years away.  Now that’s some serious elbow room!