The sun is our nearest star (about 93 million miles from Earth) and is the major source of light and heat for all the planets, moons and asteroids in the solar system. At roughly 865,000 miles wide, the sun is about 1,300,000 times larger than Earth. It is so massive that it holds all of the planets in steady orbits. But how do astronomers study the sun without going blind?
Solar space telescopes
There is a fleet of robotic telescopes in space specially designed to delve into the inner workings of the sun. The Solar and Heliospheric Observatory (SOHO) has been observing the sun for more than 25 years from its lofty perch far from Earth. It has sent back stunning images and dramatic videos of the sun’s ever-changing and explosive surface.
The Solar Terrestrial Relations Observatory (STEREO) missions were two robotic crafts that headed into space in opposite directions around the sun. For a while, they were able to capture incredible 3D images of the entire sun (both the side facing us and the side always turned away from Earth).
Skimming the sun
The largest explosions on the sun are called coronal mass ejections or CMEs. CMEs are so powerful that material breaks free of the sun's powerful gravitational pull and rockets into space at over 1 million miles an hour. When a significant CME hits the Earth’s magnetic field, the solar particles interact in a colorful dance called the Northern Lights.
CMEs are a continuous target of another space telescope called the Solar Dynamic Observatory (SDO). Launched in 2010, SDO can image these stellar blasts with incredible detail. Videos of violent solar explosions from SDO put the sun’s power on full display.
The Parker Solar Probe (PSP) has made several close flybys of the sun’s outer atmosphere, called the corona. This region of the sun can reach temperatures of 1 million degrees Fahrenheit, but PSP has escaped unharmed so far and probed the inner workings of this mysterious region of the sun. As the sun’s gravity draws it closer over and over again, the PSP will accelerate and, in 2025, will reach a speed of 430,000 miles per hour.
DIY solar viewing
Whenever you view the sun, think before you look. Do not look at the sun for more than a moment unless you are 100 percent sure you are using safe and proven viewing methods. Never use common homemade filters including CDs, smoked glass or Mylar balloons. Your vision can be permanently damaged with even short periods of direct exposure to sunlight.
The best way to directly observe the sun safely with the naked eye is by looking through either a sheet of No. 14 welder’s glass or specially made eclipse glasses. Costing between $1 and $5, these items will allow you to observe the sun’s disc, partial eclipses and maybe even a large sunspot.
Specially designed solar telescopes are available to the public as well to provide safe views of the sun and even can allow you to see solar explosions from your backyard. The views won’t be quite as good as a NASA spacecraft, but you can be a sun-watcher just like an astronomer.
Dean Regas is the Astronomer for the Cincinnati Observatory, and author of the books 100 Things to See in the Night Sky and Facts from Space! He can be reached at [email protected].
Online Classes with the Cincinnati Observatory
What: Summer Stars and Constellations: Astronomer Dean Regas leads this fun, fast and informative online class.
When: July 13, 7 p.m.
Tickets: $10 per household.
Information: If you can’t attend the live class, you’ll get access to watch the recording at your convenience at cincinnatiobservatory.org/events.
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