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Iridium Flare Traditional Cache

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jREST: Making Space

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Hidden : 12/25/2012
Difficulty:
2 out of 5
Terrain:
1.5 out of 5

Size: Size:   small (small)

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Geocache Description:

Located in the Rum River State Forest


Rum River State Forest, Minnesota

Rum River State Forest is located in western Kanabec and northern Mille Lacs counties. This state forest is broken into three areas. The largest area of the forest located between State Highway 47 and U.S. 169 just south of Mille Lacs WMA. The second area is located just west of Onamia and south of Kathio State Park and the third is located between Highway 169 and Morrison County, north of Four Brook WMA.

Satellite flare (also known as satellite glint) is the phenomenon caused by the reflective surfaces on satellites (such as antennas or solar panels) reflecting sunlight directly onto the Earth below and appearing as a brief, bright "flare".

An Iridium satellite

The Iridium communication satellites have a peculiar shape with three polished door-sized antennas, 120° apart and at 40° angles with the main bus. The forward antenna faces the direction the satellite is traveling. Occasionally, an antenna reflects sunlight directly down at Earth, creating a predictable and quickly moving illuminated spot on the surface below of about 10 km diameter. To an observer this looks like a bright flash, or flare in the sky, with a duration of a few seconds.

Ranging up to -8 magnitude (rarely to a brilliant -9.5), some of the flares are so bright that they can be seen in the daytime; but they are most impressive at night. This flashing has caused some annoyance to astronomers, as the flares occasionally disturb observations and can damage sensitive equipment.

When not flaring, the satellites are often visible crossing the night sky at a typical magnitude of 6, similar to a dim star.

While satellites may be seen by chance, there are websites and a couple of "apps" which provide location specific information as to when and where in the sky a satellite flare may be seen.


  • Heavens Above predicts when Iridium flares are visible from your location
  • Iridium flares iPhone App Free App to predict Iridium flares on an iPhone or iPad
  • Iridium flares apps for Android Free and paid App on Android
  • Iridium flares widget for Mac OS X Download free widget to get predictions based on heavens-above.com data
  • Iridium flares widget for Opera community widget for Opera Browser
  • Iridium flares prediction software (Java application)
  • Iridium page at Visual Satellite Observer's Home Page Images and further description of Iridium flares
  • Iridium Flares Podcast on 14 July 2011 from 365daysofastronomy.org

Pay attention, they happen pretty quick and may not last very long in the sky, check out this video clip of an Iridium Flare.

Here is another clip of a flare that lasts a bit longer, and gets a bit brighter in the sky... Bright Iridium Flare.

Find some clear sky and the right time, and you too may spot an Iridium Flare....

Get out and enjoy the outdoors, and keep your eyes peeled.

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