Walking in from Arcturus

(Weimer Pursell | Library of Congress’s Prints and Photographs division)

Spring’s brightest star reminds me of a furor in Woodstock back in 1993. In a town where nothing is surprising, a famous “psychic” was drawing crowds by claiming that he was inhabited by a being from Arcturus. No big deal, he said; many people’s brains are occupied by Arcturians. Such uninvited neural advisors were called “walk-ins,” and they lectured all over the US. Needless to say, the audience paid an entrance fee in terrestrial cash.

Such astroscams are easy to debunk. The “psychic,” like most people, was apparently unaware that only some five dozen stars have popular names in common use. A million other nearby stars have designations like HD212710. If aliens were to arrive, it’s implausible that they’d just happen to come from one of the few stars with a catchy name like Arcturus.

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But if I were a walk-in, I’d be proud to hail from there – and not just because it’s the brightest star ever seen high overhead from our part of the world. Arcturus is the only celestial object to have opened a world’s fair, and the only major star that will soon…disappear!

Even beginners spot it easily: The Big Dipper’s handle curves in its direction. “Arc to Arcturus” has been counseled to young stargazers almost as often as “Don’t put your fingers on the lens.”

These nights, while Orion’s army of jewels crumbles into the west to be lost through the summer, the eastern sky offers low, solitary Arcturus at nightfall. Its pumpkin-colored rays emanate from a sphere so large that 85 billion Earths could fit inside.

Can you feel any of its heat? Maybe, if you have sensitive skin. The warmth we get from Arcturus is equal to that of a single candle five miles away.

That energy was put to good use back in 1933, for the opening of the famous Chicago World’s Fair. Arcturus’ light was focused through a telescope onto a photocell, which tripped the lights to start the festivities officially. Arcturus was chosen because they believed it was 40 light-years away; the same light that left the star 40 years earlier – when a previous Chicago fair was closing – would open the new one.

A wonderful idea, even if Arcturus is now known to be ten percent nearer. But Arcturus will not stay put. Restlessly marching to a different drummer, it follows a peculiar path around our galaxy’s center that avoids the flat, pancakelike galactic plane in which our own Sun and most other stars orbit. Alone among the night’s bright stars, it springs upward out of the Milky Way’s spiral flatness, only to dive through it 100 million years later, going the other way. Instead of traveling along together like adjacent horses on a carousel, Arcturus is plunging down at us from above.

This causes rapid changes in its brightness and location. Just 500,000 years ago – a hiccup in time – Arcturus was invisible. It has been steadily approaching us ever since, and is 300 miles nearer since you started reading this. Skimming through our neighborhood, it’s now at almost its closest and brightest point. Then, half a million years from now, before we ourselves have gone even 1/200th of the way around the galaxy’s center, it will have faded into oblivion forever.

When we next return to this part of our orbit, Arcturus and its enterprising walk-ins will be somewhere else. So, greet it warmly during this one cycle in time when our paths cross – for we will never meet again.

Want to know more? To read Bob’s previous columns, visit our Almanac Weekly website at HudsonValleyOne.com. Check out Bob’s podcast, Astounding Universe, co-hosted by Pulse of the Planet’s Jim Metzner.

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