What ISS Up?

Unless you’ve been living under a rock for a while you know that there is a rather large space station in orbit above us at this very moment.  What you may not be aware of is that you can see it with your unaided eyes.

For the rock people, the International Space Station (ISS) has been in the works since the first module was launched in 1998. It is a joint operation between NASA, the European Space Agency (ESA), the Russian Federal Space Agency (RKA), the Japanese Aerospace Exploration Agency (JAXA), and the Canadian Space Agency (CSA).  It is about 167 ft in length, 357 ft in width, and 66 ft high.   Here is a picture of it from NASA:

Go here if you’d like a bigger picture: http://spaceflight.nasa.gov/gallery/images/shuttle/sts-133/html/s133e010447.html

Most of the area of the space station is made up of solar panels which, as a side effect, aids us in seeing it from the ground.  To see it you first need to find out when it is passing overhead.  There are several good sites on the internet to help you with this but my favorite is http://www.heavens-above.com.

Once you’ve gone to the Heavens Above site you’ll need to set your location by either selecting it from a map, database, or Latitude and Longitude.  For a more permenant solution you can register on the site.  Here is the home page with the area to set your location highlighted.

For this example, we’ll be viewing from here.  The track will be different from other locations and at other times.  Once your location is selected you’ll return to the home page but the Lat. Long. values will reflect your location.  Next, click on ISS and you’ll be taken to a page similar to this:

This page displays the visible passes over the next 10 days.  The meaning of most of the columns should be pretty obvious except for the “Mag” column. Mag, short for magnitude, is a measure of brightness for an object in the celestial sky.  The lower the value, the brighter the object is.  So, a mag -3.5 object is brighter than a 0 and a 0 is brighter than a 2.  For example, the Sun is a mag -26.7, the full Moon is -12.7, and the brightest Venus can appear is -4.4.  Looking at the chart above you can see that on 25 Mar the ISS will be at mag -3.2 which is very bright and easy to see.  Also note that the Mag values are proportional to the max altitude (Alt.) that the ISS will reach.    The altitude is measured in degrees from the horizon where 0 is the horizon and 90 degrees is straight up (Zenith).   For reference, if you hold your fist out at arm’s length it is about 10 degrees in width across the knuckles.

Since this may be your first time viewing we’ll click on the 25 Mar pass.  Doing so takes us to this page:

At the top of the page you’ll see a chart of the sky with the constellation lines drawn and labeled. On this chart, the pass is noted by the black arced line with the red arrow in it.  The arrow points in the direction of the pass. In the middle, you’ll see a chart detailing the time of the pass and on the bottom a zoomed in chart of the area around the max altitude (not shown here).   Be sure to notice that the East and West are swapped on the chart so that it matches the sky if you hold it up.  It helps if you are familiar with some of the constellations, but if not you can still manage.  On the chart, brighter stars are drawn larger than the dimmer stars so we can use these bright stars to find the general area to look.   For this pass we’re lucky because it tracks through the Big Dipper (I know…it’s an asterism not a constellation).  A lot of people are able to pick out the Big Dipper.  If you can already, you’re a step ahead.  If you cannot, go find it since it is up currently at night!

Once you’ve found the Big Dipper, locate the two stars at the cup end and extend a line out from the bottom until you hit a “W” shaped set of stars called Cassiopeia.   Now from the chart, you know that the ISS will pass through the end star on the handle of the Big Dipper and then into Cassiopeia.  All you have to do is start sweeping the area between these two points after the pass starts.  Feel free to find other stars along its track for extra points. Eventually the ISS will pass into this area and you’ll see it!  It’ll be easy to see because it’ll appear as a bright “star” moving in an arc across the sky very quickly.  If you see blinking lights on it, you’ve found an airplane so keep looking.

Now I know what you’re thinking, “Its not gonna pass through the Big Dipper every time.  What then?”.  Simple, look at the chart and find some objects that you can identify.  In this chart, Venus is up and it’s very bright so you can find it easily.  The Moon is also usually up and since my 3 year old can find it, I’m sure you can too.  Maybe you can use those to get going in the right direction.  But what if it doesn’t pass around any object you know?  Sorry (not really), you’ll need to learn some of the night sky!  To start, find a constellation that is pretty apparent, such as Lyra or Cygnus in the summer and Orion or Canis Major in the winter.  Once you’ve found one constellation, you can locate nearby constellations.  Pretty soon you’ll be able to pick out lots of constellations.

On a previous pass (2 Oct 2010) I took some 30 second exposure pics of the station passing.  Here are some of them.

Once you’ve seen the ISS pass a couple times you can start looking for other objects such as Hubble, the space shuttle (when appropriate), Iridium Flares (bright flashes), and the Air Force X-37 (when appropriate).

So, go forth and find the ISS!  Learn some of the night sky, which unlike all those combos you learned in Mortal Kombat, will actually still be useful knowledge in 10 years!

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