One of the great things about astronomy is its global reach. Whether you’re an occasional stargazer or an avid amateur with the latest high-tech gear, we each share the same night sky with every other person on Earth. As amateur astronomers, we share a special fellowship that reaches not only across the country, but across the world.
A few years ago, I introduced my Australian friends to the fun of looking for overhead passes of the International Space Station (ISS), in orbit since 1998. They have become avid watchers and have far surpassed my initial instructions (no worries, mate!).
My suggestion was to use Heavens Above www.heavens-above.com, a well-known and easy-to-use software package that a lot of Houston amateur astronomers use. It provides precise pass predictions for the ISS and also for visible satellites, iridium flares and radio satellites. Also available is an interactive sky chart, with a PDF print option. And for those of you with portability in mind, you can download their Android app and take the program outside with you.
Rohan, in Brisbane, uses a predictor called ISS Astro Viewer. As an example, the link below is from his location and shows the pass of the ISS near the east coast of Australia. It provides the time when the pass begins, when it is at maximum, when the pass ends and thus, is out of Brisbane’s viewing area. Look for the “brightness” bars to the right of the duration of the pass, and the date and time. Four green bars are optimal for seeing the ISS. Anything less than four green bars usually means it won’t be a good viewing.
“I’ve had quite good success viewing the ISS passes. It’s mostly the weather that prevents viewings. The software predictions in the program are brilliant. If it says it will be overhead at say 6:00-6:16pm, then it will be 6:00-6:16pm. The low angle ones (lower on the horizon) are more difficult to see.” -Rohan
John, south of Brisbane in Kincumber, uses two sites for the ISS passes and finds them complementary:
As with his friend, Rohan, ISS Astro Viewer gives John very clear predictions of when, where, and how visible a pass will be. The “display footprint” option on the second site, n2yo, really helps him to understand when the ISS will enter his particular field of view.
“The most important thing to remember is to get away from light pollution. And the most important item to take is a compass! Make sure you are lined up to be watching in the right direction, and that can be quite a challenge. I recall one night I took everything I had thought I would need out onto a sandbar that was as dark and far from lights as possible – portable computer running Stellarium, camera, etc. – everything but what I really needed, that compass. I spent the time searching the wrong direction of the sky, and so obviously saw nothing. The phasing places the visible passes in the morning for a while and then they will become evening passes. It is nice to see the ones at 9:00 p.m. A recent evening pass went into Earth’s shadow right overhead of me. Sometimes I even ride down to the shore of the Kincumber Broadwater to watch the passes without all the light pollution and interfering trees that make it less than ideal in my usual location close to home.” – John
The International Space Station, as it cycles through its orbit, is at times visible to over 90% of Earth’s inhabited surface. Though our fellow astronomers may be on another continent, ISS sightings are among the many celestial events that we have in common. The information age has given us the ability to share our love of the night sky with our friends on the other side of our planet.
Next week we’ll return home to Fort Bend County, so watch for our next post which will provide a more in-depth introduction to the Heavens Above website and some tips for using it to view the ISS, and even satellites, from the Houston area.
Until next time, Clear Skies!
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