I have created scripts for tracking satellites in Google Earth. Although I have blogged about these many times over a couple of years now, this page is designed to act a central repository for downloading these files and getting some general information about them.

What Can I Download?

These various files are for use with Google Earth (download link). They will show you the current location of different satellites that orbit the Earth. These range from the very well known Hubble Space Telescope or International Space Station to the less well known – but often visible – Iridium Fleet of satellites. KML is the geographical coding language used by Google Earth and Google Maps. A list of the available satellite tracking KML files is shown below:

• International Space Station (ISS)
• Hubble Space Telescope
• Iridium Fleet
• Space Science Collection (includes COBE, CoRoT, IRAS, Envisat, Rosat and others)
• Debris from the 2007 Chinese missile test
• Debris from the 2008 US Missile Test – There is no more debris to track.
• Debris from the 2009 Iridium/Cosmos collision
• 100 Brightest Objects in Orbit
• Advanced Satellite Tracker

Using the Advanced Satellite Tracker

This is a special script that allows you to input your own TLE data, satellite ID and other parameters. To do this download the file linked above. When it opens in Google Earth it will display the Hubble Space Telescope by default. To alter the tracker you need to enter the ‘Get Info’ properties box in Google Earth (usually right- or ctrl-click on the item in the places list). In the ‘Link’ text box you should see

http://orbitingfrog.com/cgi-bin/anyloc.pl?id=20580

This is the script that generates the KML used to display the satellite(s). You can change or add various arguments to this URL to customise the display.

• id is the satellite’s identifier in the TLE data (default is the ISS, 25544 ,this can also be set to ‘ALL’ to show all the objects in a TLE file)
• url is the source of the TLE data (default is 100 brightest objects from Celestrak)
• hor is a switch specifying whether or not to display the satellite’s horizon (default is Y)
• path is the number of hours flight path to show for the object (default is 2)
• extrude is a switch specifying whether or not to show the tether connecting the object to the ground (default is Y)

As an example, if you wanted to track the new satellites involved in the new European Galileo navigation system, you could use the link:

…anyloc.pl?id=ALL&url=http://www.celestrak.com/NORAD/elements/galileo.txt&path=24&hor=N&extrude=Y

This will show two satellites at very high altitude. A 24 hour flight path is drawn, without a horizon. The line connecting each object to the Earth is shown and the source URL is Celestrak. This is actually a very fun one to do because the Galileo satellites are very far way from the Earth and so they draw most unusual flight paths.

This script limits the number of trackable objects to 100. This is to prevent abuse of this tool as early on we had at least one person using it to track 1000s objects, which was killing my server. If you are interested in using this commercially for for very large datasets, feel free to contact me.

How Does This Work?

All objects in orbit around the Earth obey the physical laws of gravity, and thus we can predict their location over time. For every trackable object orbiting above our heads, there is a set of parameters called a two line element (TLE) set. These TLE sets are publicly available from services such as Celestrak. The models for predicting the orbit of objects is not perfect though, and so many of these objects are also tracked by radar and this new information is used to update the TLE sets every few days.

My scripts use these TLE sets to model the orbits of satellites and predict where they will be at the present time. Thanks to the up-to-date data from Celestrak and the accuracy of the mathematical models, the predicted locations are correct to within a few metres. the same models can be used to predict visible sightings of the ISS and other objects. you can read more about this on my Over Twitter page.

Feedback and Related Blog Posts

If you have comments or suggestions regarding these scripts then feel free to email me or message me on Twitter @orbitingfrog. I am always open to feedback and will get back to you when I get the chance.

Blog entries on this topic include ‘Satellites on Google Earth‘, ‘Chinese Satellite Debris in Google Earth‘ and ‘Space Telescopes on Google Earth‘. If you’re interested in satellites and, I also have a PDF of a talk about Space Junk that you might find interesting.

Here’s the lowdown on which feeds are available, how to request a new one and what they say.

What will these Twitter feeds tell me?

These feeds determine when the International Space Station (ISS), Hubble, Envisat and other interesting objects will be visible in the relevant location. They will also alert you to bright Iridium flares; elusive, momentary flashes of reflected light from the Iridium constellation of satellites. These can be often be seen in daylight! When the time approaches, an alert appears on the Twitter feed. You will get 30-45 minutes warning on the sighting opportunity.

What cities are covered so far?

So far there are Twitter feeds for Aix, Amsterdam, Anchorage, Athens, Atlanta, Auckland, Baltimore, Barcelona, Belfast, Bergen, Berlin, Birmingham, Bordeaux, Boston, Buenos Aires, Calgary, Canberra, Cardiff, Charlottesville, Chicago, Dallas, Denver, Dublin, Edinburgh, Eureka, Frankfurt, Geneva, Hannover, Helsinki, Hong Kong, Honolulu, Houston, Indianapolis, Joburg, Kaunas, Kobenhavn, Las Vegas, London, Los Angeles, Madrid, Manchester, Mauna Kea, Miami, Milton Keynes, Milwaukee, Minneapolis, Moscow, Mumbai, Munchen, New York, Ottawa, Paris, Perth, Phoenix, Portland, Prague, Providence, Quebec, Raleigh, Riga, Rio de Janeiro, Rome, Salt Lake City, San Diego, San Francisco, Santiago, Seattle, Seoul, Singapore, Springfield, St Louis, Stockholm, Sydney, Tallinn, Tehran, Tel Aviv, Thurso, Tokyo, Toronto, Vancouver, Warsaw, Wien and Winnipeg.

If you live within 20 miles of one of these cities, the data in the feed will still be correct for your location. Within 50 miles of one of these cities then the data will still be only a minute out in most cases.

Tweet alerts only appear when the weather in your location is good enough to allow the transit to be seen. The weather data comes from Yahoo! Weather.

Each tweet gives the same information, for example below is a tweet from the @oversydney feed.

The ISS will pass over Sydney at mag -1.7 at 4:32am on January 25th. Moves from 46deg elevation SW to 10deg elevation SE over 3 min.

The mag number refers to the brightness of the object on the magnitude scale, the lower the better. After that comes a pair of coordinares on the sky – the beginning and end of the track the object will make. ’46deg elevation’ means it will be 46 degrees above the horizon (where 90 degrees is directly overhead). SW and SE are Southwest and Southeast compass directions around the horizon. The duration of visibility is given as ’3 min’.

How do I get a feed for my location?

If you would really like a feed for a city near you, then feel free to email me or contact me via Twitter (@orbitingfrog). The next time I get around to adding more locations, I shall try to include your request.

RSS Feeds

Alternatively, you can subscribe to an XML (RSS 2.0) feed for visible transits in any location! Use the map below to find your location and/or drag the red marker to the right place. Click ‘Get RSS’ and the RSS feed will be loaded in a new browser window.

Or if you know your latitude and longitude, you can simply point your RSS feed reader to http:/orbitingfrog.com/overtwitter/rss.php?lat=LATITUDE&lng=LONGITUDE&place=NAME.

The skies here are big and clear and even these early Perseids look amazing. Getting the telescope out later for some real sightseeing.

Starmap costs $11.99 or £6.99.

Carnival of Space 61

President Nicolas Sarkozy’s well-known admiration for all things American now extends to space exploration. Speaking to the BBC, a senior official involved in French space policy said that it was time to shake up the European Space Agency and make it more like NASA by giving it a new, politically-led direction. The French take over the rotating presidency of the European Union on 1 July and are planning to make space policy a key area for reform.

Sarkozy is looking for UK support to bolster his ideas. He wants to lead Europe into space in a way that doesn’t leave it trailing the likes of Indian, China and Japan.

Personally, i think he could do it. This guy is crazy enough and arrogant enough to get it done.

BBC NEWS | Science/Nature | France plans revolution in space

“Almost one in four secondary schools in England no longer has any specialist physics teachers, a survey suggests.”

BBC NEWS | Education | Physics teacher shortage warning

Slacker Astronomy » Carnival of Space No. 60

With thanks to Jason, here is an awesome page about atmospheric effects on Mars, including this great dust devils animation. Mars has a rich atmosphere and this is the first planet for which we are really starting to understand the climate.

I can see why everyone loves Mars these days. Planets are just cool. Poor old Pluto…

Martian Skies – The Big Picture – Boston.com

Here is a short science experiment at home. They guy seems to be showing us how to create a plasma inside our microwaves (please be very careful if you actually want to try it). The video is hilarious though for the reaction of the guys wife/girlfriend at the very end.

YouTube – Home Made Plasma

This week’s Carnival is up so get over there and get reading!

Also found this image via the Carnival which I rather liked.

BBC NEWS | Science/Nature | Jodrell Bank future looks better

Universe Today is reporting what I have seen other sites reporting on over the past few days: a lack of sunspots. It seems there is “a small worry” that something untoward may be afoot with the current lack of magnetic activity on the Sun two years after Solar minimum.

Where are the Sunspots? Are we in for a Quiet Solar Cycle? | Universe Today

Carnival of Space #58 | Universe Today

Astronaut Ron Garan works on assigned tasks during the last scheduled spacewalk of the STS-124 mission specialist. During the six-hour, 33-minute spacewalk, Garan and fellow astronaut Mike Fossum exchanged a depleted Nitrogen Tank Assembly for a new one, removed thermal covers and launch locks from the Kibo laboratory, reinstalled a repaired television camera onto the space station’s left P1 truss,and retrieved samples of a dust-like substance from the left Solar Alpha Rotary Joint for analysis by experts on the ground.

Busy day!

YouTube – Phoenix Descends – a video from Bad Astronomy which I rather enjoyed.

Urgh.

A Case of the Plutoids | Astronomy Blog

“VLBI uses multiple radio telescopes to simultaneously observe the same region of sky. Essentially creating a giant instrument as big as the separation of the dishes. VLBI can generate images of cosmic radio sources with up to 100 times better resolution than images from the best optical telescopes.”

They are using the whole Earth as a container for a very, very big radio telescope. Hopefully there will be some very interesting results out of this arrangement in the near future.

Arecibo joins global network to create 6,000-mile telescope

Star Stryder – 2008 The Year of the Potato

Improbable Research – One into many

For a while now, I have been watching my Technorati rank gradually improve. I set myself what felt like a lofty goal of a technorati authority of 100. I am currently at 99. If you’ve ever wanted to throw me a link then now’s the time. All links to any post on Orbiting Frog help. I wanna break that barrier!

Of course after I achieve it I will need to set myself a new goal of 1000 (I’m logarithmic) which will be even harder to get. Hmm…