Skies may clear for space station flyover
Attention Space Cadets! The forecast is beginning to look more hopeful for a clear view of tomorrow evening's flyover by the International Space Station.
It's not an ideal situation. Although it is an evening event, making it more convenient for most people, the flyby is comparatively late in the evening, which means the Earth's shadow is high in the sky. So, the ISS will fly into the shadow near the highest point in its passage and disappear abruptly from our view. So expect a short view. A much better flyby is expected Friday evening, but the weather looks problematic.
So, here are the details. You should leave the house a few minutes early, to allow for any inaccuracies in your clocks, or in the orbital predictions:
The ISS will appear above the western horizon at about 7 p.m. Look for a bright, star-like object moving briskly toward the northeast. It will rise to more than halfway up the northwestern sky, and head for the W-shaped constellation Cassiopeia. There, at about 7:03 p.m., it will suddenly disappear from view. To an astronaut on board, the sun will appear to set, the windows will go dark, and the ISS will move into the "night" side of the Earth.
We'll watch for the forecast for Friday, and if it looks promising, we will post ISS viewing details here. The map below shows the path the ISS (red arrow) will take Wednesday evening. You can calculate ISS flyover predictions for your location at www.heavens-above.com
Comments
Frank,
Great info!! The ISS was just as you described. It appeared to me to have a magnitude of about a -3.5, and impossible to miss after reading your blog. Crossing my fingers for a better forecast for Friday night.
Posted by: Jeff Ceccola | January 30, 2008 8:22 PM
Thanks again for the "heads up" Frank. We observed the ISS rise exactly on schedule and then gradually dim and disappear as it approached Casseopeia. Another great viewing, courtesy of the Weather Blog!!
Posted by: Susan and Dave in Parkville | January 30, 2008 8:22 PM
Glad you caught it. It was a beautiful night for ISS-watching.
Posted by: frank roylance | January 30, 2008 10:33 PM
Hey Frank,
A colleague and I, whom I turned on to your blog, were discussing how fast the ISS appeared to be traveling. As you stated it went from the horizion to Casseopeia in the matter of minutes. We were pondering why it seemed to be traveling at such a high velocity. Any insight? We suspect it has something to do with a combination of great engineering, the "slingshot" force of the earths orbit (which neither of us know what that really is), and a degree of optical illusion. Would love to hear your thoughts!
Posted by: Jeff Ceccol | January 31, 2008 3:11 PM
Sure. It's simple (for rocket scientists) orbital mechanics. To get into Earth orbit you have to be traveling at, what else, orbital velocity. In the case of our planet, that's about 17,500 mph. And that's how fast the ISS is moving, thanks to all the shuttle flights, and Russian rocket flights that lifted its components into orbit. Each one had to achieve that speed, although, as you suggest, each launch got a little additional boost in speed from the eastward spin of the Earth. (That's why almost all these launch sites launch to the east. It takes less fuel and therefore less money.)
No optical illusions, except for the fact that it is very high - about 207 miles up - which makes it seem to cross the sky more slowly than the actual speed might suggest.
When we first spotted it last night it was probably somewhere over eastern Tennessee, at a range from Baltimore of about 787 miles. When it disappeared in the arms of Cassiopeia three minutes later, it was over southwestern Pa., about 262 miles from where we stood.
Posted by: frank roylance | January 31, 2008 3:27 PM
Frank,
Looks like the back of the front is passing through State College as of 2:45. We may see some partial clearing by 8 PM. What are specs for tonights fly over?
FDR: Check out today's latest post. Thanks for reminding me.
Posted by: Jeff Ceccol | February 1, 2008 2:44 PM