Sunday, September 18, 2011

Space Travel

For years, I have joked about Kootenay astronomers having a hard time finding work.  The mountains hide a lot of the sky. Also during the winter in the mountains, there are a lot of clouds.  Between clouds and mountains, being a sky watcher is tricky.  What we can see is quite limited which I understood every time I ventured out into the flat lands.  The prairies have so much sky.  That is the place to view the stars.

The Big Dipper
The community event offered a view of the night sky with an amateur astronomer.  My friend BJ and I decided to check it out.  Wayne had set up two telescopes by the time we arrived. With a light laser, he pointed at the Big Dipper and singled out one of the stars in the “handle.”  Through the telescope, we could see that there were actually two stars, double stars.  The two stars are also called “horse and rider,” and can be seen with the naked eye; they have been used as a test for eyesight. Mizar is really a system of stars.

The sky was perfectly clear. While we waited for Jupiter to rise, Wayne showed us two kinds of nebula, a word that comes from Latin and meaning cloud.  Nebula consists of gases, dust and matter and is the place where stars are born.  This is also how stars die.  The nebula where stars were being formed was much larger than the dying one; the other distinction is their colour.  Astronomers like Wayne are able to detect whether stars are on their way in or out. 

Our next sighting was a globular cluster which is a spherical collection of stars that are bound together by gravity.  When I looked through the telescope, I saw thousands of dots of light.  I was blown away. Our galaxy, the Milky Way, has about 150 to 158 globular clusters.  The Milky Way, Wayne told us, has over 400 billion stars.  And our sun is one of them.  And it is only a medium-sized galaxy.  It is estimated that there are 170 billion galaxies. 

I can’t even imagine what that would look like.  The numbers are dizzying and the more I looked up into the sky, I felt simultaneously how expansive the universe is and then how small we are.   What BJ noticed was how much the Big Dipper moved in the sky, and then realized that it really was us moving.

Intrigued by figuring out how fast we are moving, I called Wayne.  Here is what he said:

  • we are spinning on our axis (which we see in the 24 hour clock);
  • we are revolving around the sun (which gives us the 365 or so days in a year);
  • our sun is spinning around the hub of the Milky Way Galaxy; and
  • our galaxy is also moving.

After some research, here’s what I found about our movement through space:

  • The speed of our axis spin can be easily calculated.  The Earth’s circumference is 40,075 kilometres and there are 23.93 hours in a day.  The result of the division is 1,675 kilometres per hour. 
  • In a day, the Earth travels 2.5 million kilometres around the sun. 
  • Our solar system revolves around the galaxy at about 220 kilometres per second. 
  • And our galaxy is cruising through space at about 1,000 kilometres per second. 

We are in a hurry!

Just as Wayne promised, by 11 pm, we saw Jupiter rising in the East; the planets are on the same elliptical path as the sun and moon so they rise in the East and set in the West.  Because of the Earth’s atmosphere the best viewing was when it was higher in the sky.  When I looked through the lens, I saw four of Jupiter’s moons and dark-coloured bands.  Spectacular!

A man and his young daughter alternated telescope time with us; he told us that he just moved from Israel where he could not see the stars because of the glow from city lights.  I looked up.  The sky was getting darker and the stars were increasing. 

My mountain home is a wonderful place for star watching!

A few days later, I found my copy of Carl Sagan’s Cosmos.  This book published in 1980 follows the popular 13-part television series of the same name.  He explains the speed with which Earth is moving through the Universe.  He says, “we have always been space travelers.” 

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