Astro Bob column: See all 8 planets at dawn this week - Duluth News Tribune

If Comet NEOWISE helped you hone your ability to rise at dawn I’ve got a wonderful observing project for you. All eight planets are currently visible in a single sweep of sky through the end of the month at dawn. Tom Ruen, a fellow amateur astronomer and reader, brought this to my attention a few days ago. I ran a simulation and came up with a good viewing window. Let’s do this!

The planets are spread across 170° of sky, with Mercury low in the northeast and Jupiter and Saturn equally low in the southwest. You could stay up all night, starting with Jupiter and Saturn at nightfall and finishing up with Mercury in morning twilight, but you’d miss the satisfaction of seeing them simultaneously under one sky. Instead, I suggest you get up 2 to 2½ hours before sunrise — around 3-3:30 a.m. from many locations — and watch from a place with a clear view to the southwest and northeast. You’ll need about an hour and a half to accomplish your mission and a pair of binoculars.

Start with Jupiter and Saturn low in the southwest. Jupiter is closer to the horizon and the brighter of the two. Next, look high up in the southern sky for a bright, red-orange “star.” That’s Mars. The Red Planet has been getting brighter and brighter the past few months because our planet has been racing to meet it. They’ll be kissing cousins come October when Mars reaches opposition. At the moment, Mars is in fifth place for the most luminous nighttime sky object after the moon, Venus, Jupiter and Sirius.

Now turn to face east and you’ll spot Venus, so brilliant it’s impossible to miss. That makes four planets. While you wait for Mercury to rise, uncap your binoculars and focus them on a bright star or planet. Then use the maps to track down Uranus and Neptune. Try to see them no later than early twilight, otherwise they’ll be lost in the growing skyglow. You can also use a small telescope.

Use these maps to track down Uranus (left) in Aries (just above the head of Cetus) near the star Mu and Neptune in Aquarius near Phi Aquarii. Stars are shown to magnitude 6.5 (left) and 8.5 (right). The numbered stars in the Uranus chart are 38 Arietis, 31 Arietis, etc. I left out the full names to avoid clutter. 5° is approximately the field of view of typical binoculars. Stellarium with additions by the author

These planets are so far away — 1.4 billion and 2.7 billion miles respectively — that even though they’re both nearly four times larger than the Earth they only look like stars except through a telescope. In order of increasing distance July’s planets are Venus, Mars, Mercury, Jupiter, Saturn, Uranus and Neptune.

Now you’ll need to be patient and wait for Mercury to show up. It’s always a latecomer when appearing at dawn. The planet climbs to ~5° above the horizon about 45 minutes to an hour before sunrise when the sky starts to get bright. At magnitude 0 Mercury’s shiny enough to see without optical aid, but I suggest you seek it first in binoculars with the help of Venus and Capella.

Venus and Capella help point the way to Mercury. Or you can shoot a line from Aldebaran through Venus and continue it to the planet. While you’re at it, swing the binoculars over to Betelgeuse in Orion. Yes, Orion the hunter will soon return to the morning sky. Stellarium

Once you’ve picked up Mercury in binoculars try to see it with only your eyes. That makes seven planets. There’s just one more … the one you’re standing on. Not only does it fill up the field of view of every day of our lives, but it’s the only planet we can appreciate with all of our senses. Take a deep breath and feel good about your accomplishment.

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https://www.duluthnewstribune.com/news/science-and-nature/6590186-Astro-Bob-column-See-all-8-planets-at-dawn-this-week

2020-07-25 21:38:55Z
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