Another crisp December evening. We joined our neighbors to attend an astronomy presentation under a classic Arizona star-studded sky. We were treated to many fantastic views of the heavens through a celestron telescope. Without visual assistance, we were also able to witness various satellites that appeared like fast moving stars, here and gone as they continued in their orbit. According to our presenter, satellites and other space craft can be seen with the naked eye many times a night, depending on the situation.
The perfect balance of gravity and inertia (forward momentum) is required for natural or man-made satellites to complete their orbits flawlessly. Craft designers must adjust the speed of a satellite to "match" the curve of the earth. Imagine throwing a ball through the air. It gradually curves downward until it meets the ground. Satellites also curve downward, but due to the curve of the earth, they don't crash. The perfect amount of gravitational pull coupled with the speed of the object keeps it moving in a circular or elliptical path.
The same is true for planets and moons. The earth orbits the sun and the moon orbits the earth as each body moves due to a precise interplay of forces acting on one another. Amazingly, the design of the earth's orbit positions our beautiful planet not too close or too far to the sun, which would cause it to be too hot or cold for life. Instead, all life on earth exists because of our perfect place in space. Seasons are caused by the tilt design of our earth and is another incredible concept to explore.
Objects orbiting in space are not easy for the average person to observe, but there are a few exceptions. One intriguing craft that is fairly easy to spot is the International Space Station (ISS). International Space Station orbits earth (and catches a sunrise) every 90 minutes as it races along at 5 miles per second! You can see where the Space Station is at any given moment and view the tracker to see where it was 90 minutes ago and where it will be in 90 minutes at the ESA site. Enter your location in Spot the Station and learn when and from what direction you can expect to see ISS move over your area. There are people on board so be sure to wave!
References and Resources
Space Answers - Night Sky: How to catch the International Space Station
International Space Station
How Stuff Works - How do Satellites Orbit the Earth?
Northwestern - What Causes an Orbit?
Spot the Station - Scottsdale, Arizona
Astronomy Nights - Pinnacle Peak Park
Images: NASA - Public Domain
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