Skywatch with Bill Irwin


By the time this issue comes out, the summer season will be rolling in. The smoke of recent years has taken its toll of some of the prime observing time for most casual observers. That is August and September, when nights are dark enough and warm enough.

The sun is the dominant astronomical object of summer, of course. It is a little over 100 times farther away than it is big, so something like one-foot ball a hundred feet away and Earth is about a hundred times smaller in diameter, a small pea size. The light from the sun takes eight minutes to get here, assuming there are no construction delays. It takes me a lot longer than that to answer an email or write Skywatch. The sun is heading into solar minimum in the summer. There are longer periods with no sunspot activity and auroras will be less frequent. “Spaceweather” will be quieter. There still is a chance of a solar flare directing its energy earthward by fortunate chance, however.

During the summer you can get fascinated with astronomical dimensions. The size and distance between galaxies in the local group is comparable to the size and distance between cities in central BC, scaled way up, of course.

Since the sun and stars radiate light and heat in all directions, the intensity drops off with the square of the distance, the so-called inverse square law. You can impress your friends at your next campfire by proving it. If you double your distance from the fire, you will get four times as cold. Because Mars is the square root of two times farther than Earth, a solar panel will put out half of what it did on Earth. What do you care? You would be light there and be able to jump over cars.

Jupiter and Saturn will dominate the southern sky this summer, being in Scorpius and Sagittarius, respectively. We owe a lot to big Jove. It stands out there at five times the Earth-Sun distance and gobbles up space debris with its powerful gravitational field, debris that might otherwise make its way into the inner solar system. The sun will be about ten times weaker there by guess what law? No real business opportunities in solar there. A lot of panels for just one episode of Star Trek.

Even though there is a lot we could be worrying about down here on Earth, the stars change little during a human lifetime. There is a serenity to being out under the stars at night that surpasses even the most difficult math lessons in Starwatch. So as usual, the Bells Lake Observatory, near Horsefly, BC is open to the public, and even if you get here late, it’s a long time to the next millisecond for both astronomers and drummers alike. Contact me at irwin8sound@gmail.com.

Leave a Reply

Your email address will not be published. Required fields are marked *

WordPress Anti-Spam by WP-SpamShield