How We Observe the Sun

The great flaming disk that travels across the sky as seen from the surface of Earth, as we now know, not actually orbiting our planet. In ancient times, however, observation was limited to the tools at hand, and that was the naked eye. As science progressed we have gone from visual observation from Earth to getting much closer to the Sun, and have learned much in the process.

A Look at How we Observe the Sun

Like all objects in space, the Sun received an overcoat of mythological paint by many ancient cultures. From being carried across the sky in the chariot of a god to being a god itself, understanding of the Sun was limited by the imagination alone, but hard scientific fact was a long ways off.

Interestingly there were some early observations of the Sun that were spot on, such as an amazing calculation from Greek mathematician Eratosthenes, who in 3 BCE calculated the distance from Earth to the Sun at 149 million kilometres, a scant 1 million kilometres off the actual distance.

From the surface of Earth scientists use telescopes to see sunspots and observe the roiling surface of the Photoshpere and various kinds of equipment to record the spectrums of light and energy pouring out of the star. As soon as mankind could send some of that equipment into space the observation of the sun was expanded dramatically.

Solar Missions

NASA got the ball rolling in 1959 with the launch of Pioneer 5, following that up with Pioneers 6 through 9, up to 1968. All of these probes orbited the Sun and collected records of solar wind and the Sun’s magnetic field, all the way up to 1987. The orbits, however, were the same AU (astronomical unit, or 150 million miles) from the Sun as the Earth.

Helios 1 launched in 1970 and observed the Sun from a much closer point of view, from inside Mercury’s orbit. This and the Skylab Apollo Telescope Mount were two vantage points that brought a wealth of new data about x-ray and gamma ray emission, as well as more information about the solar wind.

NASA wasn’t the only outfit in on observing the sun. Japan’s Sunbeam Satellite was launched in 1991 and spent a decade observing an entire solar cycle.

The latest efforts from NASA are a unique observation approach called STERO, or Solar Terrestrial Relations Observatory. Two satellites were launched in 2006 and designed to move apart at the same speed, one in front and one behind Earth, providing stereoscopic imaging of the Sun and allowing for first time record of certain solar phenomena.

How Not to Observe the Sun

There is a reason people bring out shoeboxes with pinholes poked in them during an eclipse of the Sun, and why mothers the world over warn their children not to look directly at the Sun. Direct sunlight on the exposed retina of the human eye can cause a great deal of damage, and that damage can be permanent from only a brief viewing of the sun though focused lenses, such as binoculars. During an eclipse it grows darker, but the exposed parts of the sun have the same surface brightness, which means the same amount of energy is reaching the human eye, which will now absorb more because the pupil has expanded due to the diminished light.