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Most astronomy has to be done at night, when the skies are clear and the stars are out. But there’s a branch of astronomy that works in the daytime, when the Sun is blazing in the sky: solar astronomy. And their tool is the solar observatory. There are many solar observatories located around the world, and even in space. Let’s take a look at a couple and how they work.
The US National Solar Observatory operates two facilities in the United States: one at Sacramento Peak in New Mexico, and another at Kitt Peak in Arizona. Both are open to the public, and have scenic lookouts, exhibits, and live displays of the images being captured by the solar telescopes.
One of the largest instruments is the Dunn Solar Telescope, located at Sacramento Peak, New Mexico. The solar observatory is a 41.5 meter tower that continues down 58.8 meters below ground to the primary mirror. Light from the Sun travels down the tower to the primary mirror, and then on to one of size quartz optical windows in an optical laboratory at ground level. The entire tower rotates as it tracks the Sun, countering the Sun’s rotation in the sky, maintaining a smooth image.
NASA, together with the European Space Agency, launched one of its most successful spacecraft to observe the Sun: the Solar and Heliospheric Observatory. The spacecraft launched in 1995, and was only expected to observe for a couple of years, but it has been sending back images of the Sun for more than a decade.
The 610 kg SOHO spacecraft is equipped with 12 instruments that allow it to gather a tremendous amount of data about the Sun. It has also discovered more comets than anyone – or any spacecraft – recently catching its 1500th comet.
NASA has also launched its twin STEREO spacecraft in 2006. One spacecraft leads the Earth in orbit, and the other is trailing us. The two solar observatory spacecraft are then able to capture 3-dimensional images of the Sun in real time, and help astronomers better predict space weather.
We have written many articles about solar observatories, both ground and space-based, here on Universe Today. Here’s an article about when the Sun was approaching solar minimum. And here’s an article about the STEREO spacecraft seeing a tsunami on the Sun.
We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.
National Solar Observatory/Sacramento Peak
Solar and Heliospheric Observatory