Monthly Archives: March 2007

Orion

Some Musings After A Chance Meeting with Orion

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Wintery Orion
Wintery Orion from Iran

We went out to dinner with friends tonight at a local eatery. A good time was had by all and dinner was good. When we left, we stepped out into the crisp 9°F evening and there was Orion shining above us in the southern half of the sky. If it hadn’t been so cold out, we could have dallied a bit and looked at the nebula and traced out some of the other bright stars around the constellation. But, since we weren’t dressed for observing, we admired the sight as we rushed to the cars and that was it.

Weather is often cited as a good reason for NOT stargazing. It’s understandable. If it’s cloudy or rainy or snowing, there’s nothing to see. If it’s cold, you can stand it for a few minutes before you want to head back inside to get warm. On hot summer nights you just want to get back into the air conditioning or away from the mosquitos. Again, completely understandable.

But, if you’re heading back inside with a slight tinge of regret, or guilt, then I think you’re a stargazer at heart. And, you’ll find a way to get back out there to visit with the stars again.

They sell mighty fine mosquito repellant. Warm clothes can be had, or layered on. Or, you can do what I did one night during the Leonids: I sat on my car hood wrapped in a blanket, and propped up on the windshield facing Leo. It only occurred to me a few hours into the session that I COULD turn my car ON for a few minutes to warm the hood and then I would be warm, too. Wisdom in hindsight, that’s sometimes what stargazing is about, too.

If it’s cold or unpleasant where you are, here’s a little something to tide you over until the next time you go out stargazing. It’s the view of Orion from a spot in the Alborz Mountains in northern Iran, courtesy of Iranian journalist and amateur astronomer Babak Tafreshi and the Astronomy Picture of the Day web site.

outer space

Where Does Outer Space Start?

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Can You Touch It?

People tend to think of “outer space” as “out there.” Way far away. Light-years away maybe. But, it actually starts much closer to us than we think. The classical definition that describes the interface between our atmosphere and space where space starts is that “outer space” begins where our atmosphere is completely thinned out. That’s at 100 kilometers (62 miles) overhead. If you happen to fly over that limit, then you’re an astronaut. If you fly below it, you’re a high-altitude flier (whether passenger or pilot).

So, once we get above that level, we’re in outer space. Where does it end? Well, it stretches on throughout the cosmos, but when you land on another planet, you’ve left outer space and you’re back into a planetary atmosphere. On Mars, for example, you’d be inside the atmosphere at 11 kilometers (about 7 miles).

The Layers of our atmosphere From NOAA via Wikipedia
The Layers of our atmosphere From NOAA via Wikipedia

Earth’s atmosphere is pretty darned narrow when you look at it against the limb of our planet. All the life we know about, everybody we know or have known, or who has ever lived on this planet, did it inside a thin envelope of air that starts to thin out a few miles over our heads. The gravity of our planet holds the atmosphere pretty firmly in place, and radiation and particles from the Sun interact with the top of the atmosphere. It’s a lively place, this interface between Earth and space.

I’ve been reading with some interest about the companies that want to start up space tourism. There’s a company in Florida that flies people through our atmosphere in a commercial “Vomit Comet” so they can experience several minutes of weightlessness. But those still fly inside our atmosphere. SpaceShipOne, designed by Burt Rutan, made the first non-governmental human spaceflight on June 21, 2004. There will be others, and perhaps in my lifetime, regular people will be able to take off and experience “outer space” for themselves. I hope I can be one of them.