Update:

Note that the following article was for the celestial event in mid-January 2016. For more information on sky events like this one, visit our Observing News section.


Over the next two weeks, for the first time in more than a decade, you can see all of the naked-eye, visible planets — from Mercury to Saturn — together in the predawn sky.

If you follow celestial comings and goings at all, you know that bright planets have been largely missing from the evening sky for a few months. Sure, with careful watching you could have spotted Saturn low in the southwest as late as November, and Mercury put in a brief appearance a few weeks ago.

But really all the action has been in the sky before sunrise. Anchored by bright Venus and Jupiter, joined by Mars and Saturn, this planetary fab four has been dominating skywatchers' attention for months. (Did you catch last October's triple play involving Venus, Jupiter, and Mars?)

The show is far from over. In fact, during the next two weeks you'll have a good chance to view five visible planets at once. It's a real visual treat, so don't pass up the chance to see it.

(You might see posts elsewhere that suggest this event runs from January 20th to February 20th. Technically, that's true — in his book More Mathematical Morsels, celestial dynamicist Jean Meeus notes these dates. But realistically you're not going to see Mercury linger in the predawn sky for a whole month. Instead, I suggest that the last week of January and first week of February are your "best bets" for success.)

Let's set the stage. You'll need to be outside about 45 minutes before sunrise. This time of year, if you work or go to school, you're usually already up by then — maybe even well positioned to scan the predawn eastern horizon as you commute to work or head off to school.

How to see 5 visible planets at once!
Here's the view 45 minutes before sunrise as plotted for January 25th. With each passing day, Mercury will appear brighter and climb a little higher.
Sky & Telescope diagram

Venus is obvious as it lingers above the southeastern horizon. It's actually in decline, not nearly as high up as you saw it toward the end of 2015. But Venus has no equal for brightness among the night's planets and stars. Way over to the right, on the southwestern side of the sky, is Jupiter. In between are four bright beacons: not far from Venus are Saturn and, below it, the star Antares. Shift your gaze farther right to sweep up Mars, then the star Spica, and finally Jupiter.

The fifth planet is Mercury, which was spotable low in the southwest after sunset just two weeks ago. But it's been racing rapidly from evening to morning visibility. (The fleetest of planets can do that, since it circles the Sun in just 88 days.)

Your first good chance to spot Mercury before dawn comes later this week. By Friday, the 22nd, find a clear view toward southeast and look 5° above the horizon. That's about the width of your three middle fingers held together at arm's length. It's along a diagonal from Saturn through Venus, about as far from Venus as Saturn is. Day by day, Mercury will appear a little higher up and a little brighter. By month's end, it'll be easy to spot.

How to see 5 visible planets at once
Here's the view 45 minutes before sunrise as plotted for February 1st, about when Mercury should be easiest to spot. For several days the waning Moon is marching eastward among the assembled planets.
Sky & Telescope diagram

A Plane of Visible Planets

As you sweep your gaze from Mercury toward Jupiter, an arc of roughly 110°, notice that all these visible planets line along a single arc across the sky. That's no accident. All of the major planets lie very near the plane of Earth's orbit, which projects as a line — the ecliptic — across the sky. By definition, the Sun always lies on the ecliptic — and our Moon is never far from it either. It's the superhighway of planetary motion among the stars.

As you're gazing at all these planets, think about their varied distances from us. Astronomers use the average Earth-Sun distance, called an astronomical unit, as a handy yardstick for intra-solar-system distances. Of the five planets you're seeing, right now Mercury is closest (about 0.8 a.u.), followed by Venus (1.3), Mars (1.4), Jupiter (4.7) and Saturn (10.6). The reflected sunlight you see coming from Mercury took a brief 6½ minutes to reach Earth, where that from Saturn took just under 1½ hours to get here.

But don't let the vastness of interplanetary space keep you from enjoying the simple visual beauty that awaits you before dawn. We haven't had this opportunity since this time 11 years ago. Back then their order in the sky briefly matched their relative order outward from the Sun. This time, Mars and Saturn apparently didn't get the memo, but we'll happily overlook that, right?

Do you enjoy casual "eyeball" stargazing? Then be sure to listen to or download Sky & Telescope's monthly audio podcast. It's an 8-minute guided tour of "what's up" at night during January.

Comments


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January 19, 2016 at 10:35 am

very interesting you can download a program called stellerium for free and see the stars in real time on your pc or laptop

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dave-baldwin

January 22, 2016 at 12:09 pm

Or, you could go outside and look at the real thing. There's no higher "HD" than real.

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Gret

January 24, 2016 at 1:34 pm

Thanks for the tip about stellarium. I downloaded it, and I love it!

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January 19, 2016 at 11:50 am

My calculations show that you will be able to see SIX planets with your naked eye.

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January 20, 2016 at 1:06 am

how cud u see that, can u share any pic or any stuff which clearify it !!!!

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Richard-Lighthill

January 22, 2016 at 7:41 pm

The sixth planet visible to the naked eye is.... Earth ! And it is in space too!

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skybub

January 20, 2016 at 10:16 pm

I count six naked eye planets.

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January 19, 2016 at 3:08 pm

I think it would be nice to know if the show will be visible from my latitude, 56N? Mercury could be the planet difficult to spot without the help of binoculars? What do you say Kelly? In early march from Indonesia I will surley spot all five but not during the solar eclipse! Regards Jakob from Sweden

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Anthony Barreiro

January 19, 2016 at 7:24 pm

Jakob, I used the sky chart at heavens-above dot com, set the location as Karlskrona Sweden, and the time as 0730 25 January 2016, about 45 minutes before sunset. Mercury is a few degrees above the horizon. Venus and Saturn are also low to the horizon, although a bit higher than Mercury. Binoculars always help. Now I'm curious to know if you'll be able to see them all.

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Anthony Barreiro

January 19, 2016 at 8:27 pm

0730 will be 45 minutes before sunrise. But you probably figured that out already.

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January 31, 2016 at 8:27 am

No luck with weateher! Clouds dominating the scene....

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Kelly Beatty

January 22, 2016 at 9:02 am

Jakob, the alignment is much the same from 56N except that all planets will be closer to the SE-S-SW horizon. Mercury will be more difficult to spot -- best dates to see will be around 1 February +/- 3 days

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January 22, 2016 at 4:22 pm

Thanks for the answer Kelly. I still think it will be a difficult task to catch Mercury(mag 0) a few degrees above the horizon. Weather is not cooperating either

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January 20, 2016 at 5:38 am

Thank you all for your information. I will keep you updated!

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JohnnyCNote

January 22, 2016 at 6:55 am

I'm in Jacksonville, FL (30'N). How high above the horizon is Mercury expected to reach during the next few weeks? I can't believe that after all these years I still have never seen it!

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Kelly Beatty

January 25, 2016 at 2:04 pm

hey, Johnny. for you Mercury should get at least 10° high by the time the sky gets too bright. best time to look is later this week (Jan 29-Feb3)

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JohnnyCNote

January 26, 2016 at 12:30 am

Thanks mucho!

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Robert Victor

January 23, 2016 at 1:58 am

From my more favorable latitude of 33.8 deg N here in Palm Springs, CA, using 8x42 binoculars, I was able to spot Mercury the last two mornings (Jan. 21 and 22). Predicted mags. were +1.5 and +1.2. It was noticeably brighter on 2nd morning, but still not naked-eye. Any day now! On both mornings, Mercury was spotted when Sun was 11 degrees below horizon. On 2nd morning (Jan. 22), could follow Mercury until civil twilight, when Sun was 6 degrees down. Of course the view of all five planets at once was wonderful. Looking forward to following it until end of February, because it will be much brighter than now, though lower in twilight. Abrams Planetarium Sky Calendar also depicts 5-planet span for Jan. 25 and Feb. 1, same as in your excellent article!

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texadactyl

January 23, 2016 at 8:09 pm

I find stellarium most useful as a planning tool. I like to be in the right place at the right time!

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January 24, 2016 at 3:56 am

Hello, I live in Lagos, Nigeria (West Africa), will I be able to see these pre-dawn planets in the coming weeks as well judging from the differences in time zones?!

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Kelly Beatty

January 25, 2016 at 1:59 pm

hi, Tomyde, don't worry about time zones -- everything is relative to your local time of sunrise. And because Nigeria is so close to the equator, it is actually easier for you to see Mercury, because it will be almost directly above where the Sun rises, instead of off to one side. good luck -- and let us know if you see all five planets!

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