Title Bar - Cosmology

Other Resources for Measuring Parallax

Unfortunately, this technique is limited by the size of the Earth's orbit and also by the Earth's atmosphere which blurs any parallax less than 1/50 arc second footnote15. So, for stars more than 50 parsecs away another method of distance measurement is needed.

Some Modern day experiments avoid these problems by sending satellites into space to measure parallax. This makes the orbit slightly larger and eliminates much of the atmospheric blurring. Two such projects are the HIPPARCOS satellite (http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/hipparcos.html) and the SIM mission (http://huey.jpl.nasa.gov/sim/).

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