17 June 2005

Goes is Going

Posted by Dan Satterfield

We have a new weather satellite going up later this month. Goes N will be launched (hopefully) on 24 June. This is the first of a new series of geostationary weather satellites.

GOES N will eventually become GOES 13 and replace GOES 12 which has done a great job for the last several years.

GOES images are the ones you see on TV every night during my weathercast. (and every one else’s for that matter!)
They are one of the most visible symbols of advanced science technology that people come into contact with on a daily basis (I’d be willing to bet I will get an argument on that assertion though!)

This new GOES will have significant improvements over the current one. We will also likely get the images faster and the pointing accuracy is greatly improved.

In case you do not know. GOES stands for Geostationary Operational Environmental Satellite. These satellites are placed at an altitude of 35,786 km. If they break, there is no rescue from the space shuttle since it can go no higher than around 500km in altitude.

Why so high?? Because at this altitude, a satellite will circle the earth in 1,436 minutes. It so happens that the earth takes just that many minutes to rotate on its axis. Thus, the satellite hovers over the same spot on earth, above the equator all the time.

If you do the math you will find out that 1,436 minutes is 23 hours and 56 minutes.
You thought the earth turned once every 24 hours exactly, didn’t you.


So why does the sunset not change by 4 minutes each day. It should since we are on a 24 hour clock and the earth turns once in 23hr. and 56 mins. I suspect you know. If not…I’ll let you look that one up yourself!