Cumberland-Times Sky Columns
May 2005

May 1 - Top Sky Sights
May 8 - Have Fun Learning
May 15 - Planets and Jogging
May 22 - Websites on Space
May 29 - The Worlds of Star Wars

May 1 - Top Sky Sights

Now that the cold weather is nearly gone, sky gazing is more fun. The top May sight is the Big Dipper high in the North with its handle pointing to Arcturus, Spica and Jupiter in the South. Another May 2005 sight is the Eta Aquarid Meteor Shower, peaking this Thursday about 4-5 a.m. Meteor showers are named from the region of the sky from which they seem to stream from (the star group Aquarius for this shower). But the meteors (pieces of space rocks burning up in our upper atmosphere) can be seen all across the sky. Two special events occur on May 19. In the 4 a.m. southeastern sky, the bright planet Mars appears only about a degree (two moon widths) to the left of the planet Uranus. A binocular will allow you to see Uranus, through Mars' glare (Mars is more than 100 times as bright as Uranus). On the evening of May 19, the nearly full moon appears near the planet Jupiter. Our full moon on May 23rd appears near the star Antares, marking the heart of the Scorpion. At the end of May, the planet Venus can be seen low in the western dusk, setting more than an hour after sunset.

May 8 - Have Fun Learning

Many people would like to know more about our universe. What stops them is the feeling that Astronomy involves a lot of math or complexity. Even looking at one of the 'Dummy' or 'Complete Idiot' books on space makes them feel overwhelmed. (I think that even these books have too much information for beginners; so when you when you look at their titles, it makes you feel even worse!) There are some very nice books for beginners if you look around. This column gives three brief reviews of books that I think most beginners will enjoy.

In the Allegany County libraries is "The Kingfisher Young People's Book of Space" by Martin Redfern (J 520 R). Contents include: Exploring Space, The Solar System, Stars, Out in Space, Back in Time and Cosmic Questions. Each page is about half text and half well matched illustrations. The book was copyrighted in 1998; only a few small corrections are in order. (The Mir Space Station left orbit four years ago and has now been replaced by the International Space Station (ISS).) There are many interesting topics, suitable for discussions by both young and adult readers. The book ends with a well written glossary.

While I was visiting a local school, there was a book fair. I purchased a copy of "Children's Night Sky Atlas" by Robin Scagell, a 2004 Dorling Kindersley book. Contents include: Our Place in Space, Looking at the Night Sky, How To Use This Atlas, a series of plates showing all the stars visible to the eye from both hemispheres (showing both a natural sky redention and a labelled counterpart), a chart for each month of the year accompanied by tips of the more significant objects then seen, a glossary and an index. This book is spiral bound (allowing it to be laid flat for use while stargazing). The transparent overlays of the main constellations are the best I have seen. At a price of $20, this book is highly recommended for beginner's both young, adults and seniors.

At another book fair at a local hospital, I purchased "Astronomy" by Kristen Lippincott, a Dorling Kindersley Eyewitness book copyrighted in 2000. Contents include: The Study of the Heavens, Ancient astronomy, Ordering the Universe, The celestial sphere,......, Travelers through space, The birth and death of stars, Our galaxy and beyond, and index. This book gives you a very fine intro
look at the key areas of astronomy. In some ways "Astronomy" is similar to the Kingfisher Book of Space but at a higher reading level. Other books in the DK Eyewitness series include: Rocks & Minerals, Bible Lands, Ancient China, Energy, Renaissance, Soccer and Media & Communications (a total of 118 and counting). "Astronomy" is a fine book to order from a local book store, costing about $12.

May 15 - Planets & Jogging

What does jogging have to do with the planets? Just as there are fast joggers and slow joggers, there are fast planets and slow planets (in their motion about the sun). If we have a fast jogger and a slow jogger on a track, eventually the faster jogger will pass or lap the slower jogger. In competitive races (like the 5,000 meter run) the faster runners will often pass or lap the slower runners. When one runner passes another runner, it is similar to one planet passing the other. This time of closest approach by planets is called opposition (the farther planet then appears directly opposite the sun). Since the time of opposition can be directly observed, we can use this information to actually determine the length of a planet's year in terms of the Earth's year.

To understand the math behind finding a planet's year length, let's go back to the joggers along a track. Suppose the fast jogger (someone like our President) can run around the track in 90 seconds. Let the slower jogger run around the track in 120 seconds. If both joggers start together, then how long will it be before the faster jogger laps or passes the slower jogger? Well, each seond the faster jogger moves 1/90th of the way around the track. In one second, the slower jogger moves 1/120th of the way around the track. So each second the faster jogger gains (1/90 - 1/120) = (.0111 - .0083) = 0.0278 of the way around the track. Then to gain one lap, it will take 1/(.00278 ) = 360 seconds or 6 minutes. To check this result, in 360 seconds the faster jogger runs around the track 4 times (as 90 x 4 = 360 seconds) while the slower jogger runs 3 times around the track (as 120 x 3 = 360 seconds).

Now let's replace the faster jogger with the Earth. Mars can be the slower jogger. The Earth takes 365.24 days to orbit the sun. So each day, the Earth travels 1/365.24 of the way around the sun. The planet Mars every 780 days makes a close approach to the Earth. This means that each day, the Earth gains 1/780 of the way over Mars. How fast must Mars move each day around the sun?

Recall the jogger problem where the fast jogger's rate - slow jogger's rate = rate of overtaking. Then we can say that the fast jogger's rate (Earth's rate) - rate of overtaking = slow jogger's rate (Mars). Then these numbers tell us that 1/365.24 - 1/780 = 0.002738 - 0.001282 = 0.001456. That means each day Mars travels 0.001456 of the way around the sun. That means that Mars takes 1/0.001456 days to orbit the sun, which is 687 days. So our neighbor planet Mars takes about 1.88 of our years to move around the sun. So a Mars' year is nearly two of our years. The same approach can be used for the other outer planets. We learn that Jupiter takes 11.86 Earth years, Saturn takes 29.46 years, etc....to orbit the sun. So from a moving platform (the Earth), we can determine the orbital period or year length of the other planets.

May 22 - Websites on Space

Earlier this month, I reviewed three very good star guides. Today's column will deal with websites on space for youngsters and interested adults. As I mentioned earlier, sometimes material suited for juveniles is actually superior to material touted for adult beginners. I recommend three websites in this column. Next month, I will review some additional websites. You don't need to have your own computer; you can just go to a nearby public library where you can sign up for a computer with an internet connection. (My nearby library (LaVale) allows you to sign up for a half hour at a time.)

First is http://spaceplace.nasa.gov/en/kids/. The opening menu includes Games, Projects, Animations, Cool Subjects and Amazing Facts. In Projects, you can print out (using Adobe), an evening constellation map for each month that you can fold up and play games with your friends. In Animations, there is a Cannon that you can fire to put its cannonball into orbit. Cool Subjects includes Planets & Solar System, Laws of Universe, Stars, Galaxies & Black Holes and Earth & Moon. Amazing Facts includes some interesting topics such as "What Spacecraft Gets the Best Mileage?" Spaceplace also has a Spanish version.

An older commercial website is http://KidsAstronomy.com . (Commercial means they have ads for children's science materials to allow them to finance their website.) KidsAstronomy has a wide array of areas including games, free online courses, an Astronomy Dictionary, Space Exploration, Deep Space and eyecatching solar system displays of each planet and its moon(s). I liked the fast facts listed for each planet (can be printed out).

A third website is www.livescience.com which is a general science website at the middle school level. Just as KidsAstronomy, Livescience is a commercial website with ads for science related products. Livescience's top menu bar includes the areas: Animal World, Human Biology, Forces of Nature, Environment, Technology, Science of Fiction and History. I found many of the headlines intriguing, which include "New Radar Aims to Improve 75% False Alarm Rate on Tornadoes", "Sumatran Quake Left 'Scar' on Earth's Gravity" and "Antarctic Glaciers Melting Rapidly".

May 29 - The Worlds of Star Wars

By now most science fiction fans will have seen or heard a great deal about The Revenge of the Sith, George Lucas' final installment of Star Wars. I have enjoyed all the Star Wars films. But are the planetary settings realistic?

This column will comment on the planets seen throughout the first three episodes.

Episode I - The Phantom Menance opens on the planet Naboo, a tropical world with swamps and dry land. Naboo is quite unusual in that it lacks a solid or molten interior. The Jedi Qui-Gon and Obi-Wan (with Jar-Jar Binks) pilot their submersible ship through many watery passageways (complete with obligatory monsters).

The only planets in our system with huge amounts of water and ice are Uranus and Neptune, gas giants with dense cores (that produce their magnetic fields). Here the ice and water would comprise the mantle of these planets but the rock would have sunk to the center and not be interspersed with the ice/water.

The next planet in Episode I is Tatooine, a desert world that orbits two suns (stars). Tatooine is the home of the youthful Anakin Skywalker. Tatooine resembles the planet Mars but with a much thicker atmosphere. A planet could have a stable orbit about two suns, if the planet's orbit was much larger than the spacing between the stars (that would orbit about each other).

Episode I also features the planet Coruscant, the capitol of the Galactic Republic. Coruscant seems to be much like the Earth but covered with tall buildings on the scale of our Earth's tallest buildings.

Episode II - The Attack of the Clones features Coruscant, Naboo, Tatooine and the Mars-like planet Kamino (where the cloned fighting machines are assembled). Cloning in Star Wars means that one warrior's fighting skills and personality are encoded in the brains of the cloned fighters.

Episode III - The Revenge of the Sith opens on Coruscant. The next planet seen is Utapu, where the cities are in underground caves. There is finally a green (vegetation) planet, Kashyyk. This is the home world of the Wookies, including Chewbacca (Han Solo's hairy sidekick in future episodes).

The great duel between Obi-Wan and Anakin Skywalker takes place on the volcanic world of Mustafar. At the end of Episode III, the Skywalker twins are separted, being sent to Tatooine (Luke) and the planet Alderaan (Leia). Jedi master Yoda escapes to the swampy planet Dagobah, featured in Episode V.