Cosmic distances are deceiving


Tom BurnsStargazing

Tom BurnsStargazing

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The ringed planet Saturn is in the constellation Libra right now. To find it, look low on the southern horizon just after dark for a pale-yellow point of light up and to the right of the head and claws of the constellation Scorpius. Saturn will be the brightest “star” in that direction.

Saturn, like Earth, is a planet. It orbits the sun and is very close to us, at less than 900 million miles away.

The stars of Scorpius are, of course, distant suns. Antares, sometimes called the Heart of the Scorpion, is the brightest star in the constellation and one of the brightest in the night sky.

At over three quadrillion miles away, it is considerably more distant than Saturn. The light from the sun bouncing off Saturn takes about 80 minutes to get from the planet to your eyeballs. The light from Antares journeys 550 years.

Saturn is a cold ball of mostly hydrogen gas 75,000 miles wide. By comparison, Earth is an even punier 8,000 miles wide. Its rings span over 200,000 miles, nearly the distance from Earth to its moon. Saturn shines dimly with light reflected from the sun. The light source is nearly a billion miles miles away from it.

Antares is a supergiant star, an exploding ball of hydrogen generating 10,000 times the energy of our sun.

And it is huge, even by starry standards, at 1,766 times the diameter of our own star, the sun. If we placed Antares at the center of our solar system, it would extend well past the orbit of Mars.

Yet Saturn’s brightness exceeds Antares’ relatively fainter glow. Even a small telescope will show its mind-altering rings. Saturn’s brightest and largest moon, Titan, which is only a few thousand miles in diameter, is visible in a small ’scope or binoculars.

In even the largest telescope on Earth, giant Antares will still look like a tiny point of light.

Distance makes all the difference, of course. You can see a mosquito much better than the Empire State Building if the mosquito is perched on the tip of your nose and the Empire State Building is in New York City. Even a large island like Great Britain wouldn’t look like much at this distance in a small telescope.

Just to the right of Antares, you will find such an island of stars — hundreds of thousands of them — packed into a relatively dense ball called a globular cluster. M4, as it is called, shines with the combined energy of 40,000 of our suns. At more than 450 trillion miles wide and 7,200 light years away, it is over 13 times farther away from us than Antares.

The problem of distance strikes again. In a small telescope or binoculars, all those glorious stars taken together look like a little, fuzzy blob. In a larger scope, you will begin to discern individual stars, but they will be exceedingly faint.

Only those small-telescope nuts with considerable experience (and a good imagination) will begin to see the glory present in that fuzzy patch.

That’s to be expected. We feel the pain or joy of someone near and dear to us with much greater passion than we do the ups and downs of entire cultures far away. The death of a relative is a crushing blow to all of us. Sadly, the terrors of Somalia and the genocide in Rwanda are — for many of us at least — a vague abstraction and a fading memory.

Saturn is our cosmic sibling, so close we can learn to love the weird idiosyncrasy of its rings. They are more far impressive than a ball of 200,000 stars, even though our sister planet is, like our own, an inconsequential speck of dust compared with the glorious spectacle of a globular cluster isolated from us by the vastness of space.

Tickets are still available for Perkins Observatory’s “Celebration of the Sun” program starting at 4 p.m. Saturday. Please call 740-363-1257 for details and to reserve tickets.

Tom Burns is director of the Perkins Observatory in Delaware.
Tom Burns is director of the Perkins Observatory in Delaware.