Four Planets Meet in the October 2015 Night Sky! | Almanac.com

Four Planets Meet in the October 2015 Night Sky!

Bob Berman
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The wild morning display continues! See four planets performing the year’s best conjunctions. It’s bright and easy.

This coming weekend, Saturday morning October 17, and Sunday the 18th, the two brightest “stars” hover together. It all happens 45 minutes before sunrise, and you’ll need a clear view toward the east.

  • The topmost, brightest “star” is Venus.
  • The “star” below it is Jupiter.
  • With those planets identified, now look next to Jupiter for a faint orange star. That’s Mars.

All three planets are easy to see in the morning twilight.

Those worlds keep hanging together all next week, so you can really look eastward any clear morning before dawn, whenever you’ve had enough coffee.


Mercury’s Best Appearance in 2015

Now for the icing on the cake. The three planets just mentioned are not super low. But if you have—or, can get to—a clear shot all the way down, if you live on a farm or a ridge, you’ll see a fourth planet. This one’s bright, too, and far beneath the others. This is Mercury, in its best appearance of 2015.

If you draw a line from Venus to Jupiter, Mercury is on this line near the horizen. That innermost planet is odd in so many ways.

  • Radar pulses we bounce off Mercury show that it makes three rotations, three Mercury days, in the same exact interval as two of its years. This causes Mercury’s sunrises to happen 176 days apart. That’s the longest interval between sunrises of any object in the known universe.   
  • Then, too, Mercury’s orbit is so out-of-round, its surface suffers from a sun intensity that varies from 6 to 14 times what we experience. When it’s closest to the sun you want to be sure to use SPF 2 billion sun block instead of your usual 1 billion.
  • As if to jealously resent Venus’ greater dazzle, Mercury may smash it to pieces.  Thanks to gravitational tugs from distant Jupiter, the Mercury orbit wildly changes shape. Someday it may actually orbit right into innocent Venus. Such a collision may happen in the next five billion years, and could destroy both planets.
  • Mercury has no tilt. So at its poles, in any crater or depression, you’d never see the Sun at all. Result: Permanent dark places. They’re filled with ice. They offer winter sports on a world badly needing it.

The next 10 days provide the year’s best chance to easily see that planet. Low in the east, 45 minutes before sunrise. And as a bonus, you get another three worlds thrown in for free.

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