Look... Up in the sky... It's the International Space Station main content.

Look... Up in the sky... It's the International Space Station

by Joe Rao on

Hayden Planetarium Blog

Echo I Satellite
The 135-foot rigidized inflatable balloon Echo I satellite undergoing tensile stress test in a dirigible hanger at Weekesville, North Carolina in the early 1960s.

When I was a youngster growing up in the Throggs Neck section of The Bronx, the Hayden Planetarium had a service called Dial-a-Satellite.  When you called a special phone number, you could hear a recorded message telling you when and where to look for the brightest naked-eye satellites that occasionally tracked across our local New York skies.  Back then (and I'm speaking now about the mid-1960s) the only really bright satellites readily visible were actually two giant Mylar balloons... measuring about 100-feet in diameter which orbited Earth at altitudes of about 1000 miles.

These were the Echo passive communications satellites: they actually functioned as reflectors, not transmitters. After being placed in orbit around the Earth, a signal would be relayed to one of the two Echo satellites, which were reflected or bounced off its surface, then returned to Earth. The Echo satellites were easily visible to the eye because of their highly reflective surface, but also because of their low orbits; they would appear from below one side of the horizon, cross the sky, then disappear below the opposite horizon after crossing the sky, as happens with all low Earth orbiting satellites. These spacecraft were nicknamedsatelloons by those involved in the project. Today, those two Echo satellites are long-gone, but there are now literally thousands of satellites orbiting our Earth.

By far and away, the biggest object now orbiting our Earth is the International Space Station.  And if our skies are reasonably clear on Saturday, November 22, we here in the Tri-State Area will have a great opportunity to see the ISS make a long, high pass across the evening twilight sky.


It will be moving along a track that will take it roughly from Washington to just north of New York and then on toward Boston and the Gulf of Maine; it will briefly overfly our region about an hour after sundown.

It always amazes people when they are told that they can actually see the Space Station—now orbiting 218 miles above Earth—with their own two eyes; no optical aid is needed.  As big as a football field, the ISS is visible by virtue of sunlight shining on its metallic skin and large solar panels.  To the unaided eye it appears as a very bright star that does not twinkle and shines with a slight yellowish-white tinge. Check out this short video of it when it passed over Gloucester, Massachusetts back on Christmas Eve, 2006.

Some assiduous astronomers have even been able to photograph the actual structure of the Space Station by tracking it with their telescope:

ISS Photographed from Ground
A composite of images of the International Space Station from a ground-based telescope.
© Dirk Ewers, 2008

On Saturday, the ISS will emerge from above the southwest horizon at 5:32 p.m. Prepare yourself for this ISS pass by getting outside some minutes before it's due to appear and getting yourself acclimated to the sky and the surrounding stars.  Certainly, you will immediately notice two very bright, non-twinkling silvery stars low in the southwest.  They are not stars, but planets; the brighter and lower of the two is Venus, the other will be Jupiter.  Make a fist and hold it out at arm's length.  When the ISS first appears, it should be roughly "two fists" to the right of Jupiter and Venus.  It will appear to move straight up to a point almost directly overhead.  It will then drop down toward the northeast, disappearing about 3-minutes after it first appeared, near to the northeast horizon.  It actually will seem to rapidly fade out toward the end of its track as it moves into the Earth's shadow.

ISS Trajectory Nov 2008
Path of the International Space Station on November 22, 2008 between 5:32 and 5:35 p.m.
Image © Heavens-Above, GmbH

As to just how bright it should get, it should be plainly visible even from brightly lit cities; only Venus and perhaps Jupiter will be brighter.  So during it's 3-minutes of visibility, the Space Station will be one of the three brightest objects in the sky!

And keep in mind that as you look at it, there are ten people who are currently onboard.  Three are semi-permanent residents, staying for upwards of six months on the ISS.  The other seven just recently arrived on the Space Shuttle Endeavour which was launched from Florida on November 14.  The Shuttle is currently docked to the ISS and is scheduled to return to Earth on November 29.

Pretty neat, huh? Tell all your neighbors... and take the kids out for a look.

I'll be interested to see how many plan to check it out, so drop me a line if you see it.