Extremely Close Venus-Jupiter Conjunction Next Saturday!!

[Sureshks]

Jupiter-Venus 8_00pm.png

Jupiter-Venus 5_31pm Closest Approach.png

Hi all,

See my write-up (below) that I posted on the MAS FB page today (https://www.facebook.com/MinnesotaAstronomicalSociety/).

Let me know if you are planning to come out to ELO next Saturday at 7:00pm to see it!!

Get ready for a truly spectacular alignment of planets next week!!!

On Saturday August 27th Venus will pass just 4' to the north of Jupiter in the evening sky, during what is called a planetary conjunction (technically, it is an appulse, a much rarer type of conjunction). Our Moon is, on average, 31' in diameter when viewed from Earth (1/2 of one degree). So the closest gap between Venus and Jupiter during this conjunction will be just 1/8 (13%) the apparent size of the Moon!!!

That's so close that most people won't even be able to separate the two planets without using binoculars or a telescope!! For scale, find the visual double star Alcor and Mizar in the Big Dipper (the 2nd star from the end along the handle). The ancients used their very close 12' separation as an eye test. Jupiter and Venus will be separated by only 1/3 of that distance!!

Closest approach between Venus and Jupiter will be at 5:31pm CDT in the late-afternoon next Saturday. Unfortunately, the Sun will still be up then in our sky. But it is possible to locate and view these bright planets in broad daylight using a telescope of least 3-4" aperture. The bigger the telescope, the better! Please use care when looking for them through a telescope since the Sun will be only 22 degrees away to the west!!

Venus, though much smaller than usual (just 10.8") because it's on the other side of the Sun from us, will still be easier to view in daylight through a telescope than fainter Jupiter, even though Jupiter will appear 3 times larger. However, I've been able to clearly see Jupiter's reddish equatorial bands in broad daylight, through even my little 3.5" telescope. Jupiter's moons, however, won't be visible until closer to sunset, unless you use a much larger telescope.
By sunset at 7:58pm the planets will have begun drifting apart again, and will be separated by 7'. But I find the pairing to appear even more interesting than during closest approach. Jupiter's moon Callisto orbits 1.17 million miles from the gas giant. On this night it will be near it's furthest western separation from its parent planet in it's 16.7 Earth-day orbi. Through a telescope it might seem more like a moon of Venus than of Jupiter! See the attached picture for further details...

For those without a telescope, you'll have to wait till dusk to spot the pair, when they will be very low along the western horizon. You will need an almost perfect western horizon to see them when they finally pop out naked eye, around 8:20pm or so. Binoculars will help. The duo will set just a half-hour later, by 8:51pm... only 53 minutes after sunset.

We're actually quite lucky to have even this brief time in evening twilight to view a planetary pairing this close. Due to orbital geometry, most very close conjunctions occur too close to the Sun to see at all -- because increased distance to the planets shrinks their apparent orbital eccentricities (or, their variance from the ecliptic plane), from our viewpoint... making them appear closer together. At the time of this conjunction, Venus will be 143.3 million miles from Earth, while Jupiter, eleven times the diameter of Venus, will be 4 times as far from us, at 590.9 million miles.

I did some checking and cannot find such a close pairing of Jupiter and Venus in recent history. The closest I was able to find occurred on August 18, 2014, when the pair were just 11.9 apart. The next very close pairing won't occur until 6:35am CDT on August 22, 2065, when Venus will actually pass in front of (occult) Jupiter!

See these articles for more information:
http://www.space.com/33792-venus-jupite ... ction.html
https://jeffreylhunt.wordpress.com/2016 ... njunction/
http://www.virtualtelescope.eu/2016/07/ ... -aug-2016/

FYI -- The Minnesota Astronomical Society's Eagle Lake Observatory (ELO) will be hosting a public viewing night next Saturday, starting at 7:00pm. So come out before sunset to catch these planets while they're still higher up in the sky and easily seen in the large telescopes on-site!
To get to ELO from the Twin Cities, take US 212 west to County Road 33 (at Norwood, MN) and go north about 3 miles to Baylor Regional Park. ELO is straight ahead up the hill within the park. The MAS does not charge for public viewing nights, but Carver Parks charges $5 per vehicle to enter.

About ELO: http://www.mnastro.org/facilities/elo/

Map to Baylor Regional Park: https://goo.gl/maps/qfvGXww53t52

So come join us for this very rare and special celestial event!!!

Suresh Sreenivasan
MAS Board Member At-Large
BSIG Coordinator

16" f/4.9 Homemade Dobsonian on Tracking Platform
12" f/4.9 Orion Dobsonian Push-To
9.25" f/10 Celestron CPC SCT
4" f/6.4 Borg Refractor on Vixen GPD Mount
3.5" f/13.8 Meade ETX Maksutov-Cassegrain

[Deane Clark]

I think you meant Mizar and Alcor have a 12' separation, not 12".

[Sureshks]

Thanks for fact-checking. I fixed it... are you coming out that night?

[tugger]

I have to work so I'm counting on someone to image it for me!

[Deane Clark]

I'll be there, assuming it's not clouded out.