John Lehnert, age 8, of Dana Point, California, for his question:
How do scientists study the sun without going blind?
Scientists can tell us how hot and heavy the sun is. They know just what it looks like close up and a lot about its storms, its sudden flare ups and enough other details to fill volumes. It is natural to wonder how they learned all this without going blind.
Scientists, of course, are sensible people. They never risk harming their eyes by staring directly at the dazzling face of the sun. If someone told them to look at it through a telescope, they would be even more horrified. The eyepiece acts like a burning lens strong enough to blind a human eye. But scientists are curious people much too curious to be stopped by the brilliance of the sun. Instead of giving up, they got busy and invented dozens of different ways for studying the sun without actually staring it straight in the face.
One of their tricks is very simple and if you have a small telescope you can try it. Fix a screen of white cardboard behind the eyepiece and point your telescope at the sun without peeping. Fiddle around with it until the image of the sun is properly focused on the screen. You can stand around with several friends and watch the picture image of the sun. Astronomers use a fancier gadget in their observatories. They have a tall sun tower with a domed top. Mirrors and lenses relay the sun's image down onto a screen at the bottom of the tower.
An observatory has all sorts of other gadgets for studying the sun indirectly. A coronagraph blots out the face of the sun and shows only the filmy corona around it. This halo of gases often seethes with fiery outbursts. The sun tower most likely has a spectroheliograph. "Hellos" means the sun and the "spectrum" is a row of bands of color that can tell an expert which gases are present. A modern observatory also has radio telescopes. They catch radio signals from stormy tantrums on the sun. Many of the gadgets used to study the sun are fitted with cameras. The scientists study the photographs without ever looking at the sun themselves.
The world's grandest system for studying the sun is in Australia. It is a great circle more than 1 3/4 miles wide and six miles around. The rim is a monster radioheliograph for catching radio signals from the sun. It has 96 antennas, placed 320 feet apart. Each tall dish of wires is 45 feet wide. Together they keep a de¬tailed record of spurting radio signals from the sun. The center of the circle has telescopes, cameras and computers. The telescopes watch what is happening on the sun from dawn to dusk. The cameras take pictures of the radio signals and also the plain sights of the sun. The computers compare the news from the telescopes, radiotele¬scopes and lots of other mechanical sun watchers. And the marvelous system works al¬most by itself. Scientists in the control rooms just study the reports.
Sunspots and other raging upsets on the sun upset radio and telephone systems here on earth. It helps us to know what to expect in advance. And this happens to be a year when a big rash of sunspots is expected. The wonderful system of automatic sun watching in Australia is all ready to keep us informed. It scans the whole face of the sun by itself. Its computers switch the cameras on and off to take radio and telescope pictures every few seconds. Experts do not even have to wear dark glasses to study the reports that come in moment by moment.