5 Days, 2 Spectacular Conjunctions

Two planets close and up close. This is the view through a telescope during the extremely close conjunction of Jupiter and Venus on August 27. Credit: Stellarium

Conjunctions of bright planets make for jewelry in the sky. This week, get ready for some celestial shimmer. If you’ve been following the hither and thither of Mars and Saturn near Antares this summer, you know these planets have been constantly on the move, creating all kinds of cool alignments in the southern sky.

On Tuesday night (August 23) the hopscotching duo will fall in line atop Antares in the southwestern sky at nightfall. Mars will sit just 1.5° above the star and Saturn 4° above Mars. Viewed from the Americas and Europe, the line will appear slightly bent. To catch them perfectly lined up, you’ll have to be in central Asia on the following evening, but the view should be pleasing no matter where you live.

Nice as it is, the Mars-Saturn-Antares lineup is only the warm-up for the big event: the closest conjunction of the two brightest planets this year. On Saturday evening, August 27, Venus and Jupiter will approach within a hair’s breadth of each other as viewed with the naked eye — only 0.1° will separate the two gems. That’s one-fifth of a full moon’s width! While Mars and Saturn will be a snap to spot low in the southwestern sky during their conjunction, Venus and Jupiter snuggle near the western horizon at dusk.

To make sure you see them, find a place in advance of the date with a wide open view to the west. I also suggest bringing a pair of binoculars. It’s so much easier to find an object in bright twilight with help from the glass. You can start looking about 25 minutes after sunset; Venus will catch your eye first. Once you’ve found it, look a smidge to its lower right for Jupiter. If you’re using binoculars, lower them to see how remarkably close the two planets appear using nothing but your eyeballs. Perhaps they’ll remind you of a bright double star in a telescope or even the twin suns of Tatooine in Star Wars.

Have a small telescope? Take it along — Jupiter and Venus are so close together that they easily fit in the same high magnification field of view. Jupiter’s four brightest moons will be on display, and Venus will look just like a miniature version of the waxing gibbous moon. Rarely do the sky’s two brightest planets nearly fuse, making this a not-to-miss event.

If cloudy weather’s in the forecast that night, you can still spot them relatively close together the night before and night after, when they’ll be about 1° or two full moon diameters apart. I get pretty jazzed when bright objects approach closely in the sky, and I’m betting you do, too.

I also don’t mind being taken in by illusion once in a while. During a conjunction, planets only appear close together because we view them along the same line of sight. Their real distances add a dose of reality.

On Saturday evening Venus will be 143 million miles (230 million km) away vs. 592 million miles (953 million km) for Jupiter. In spite of appearing to almost touch, Jupiter is more than four times farther than the goddess planet.

That distance translates to the chill realm of the giant gaseous planets where sunlight is weak and ice is common. Try stretching your imagination that evening to sense as best you can the vast gulf between the two worlds.

You might also try taking a picture of them with your mobile phone. I suggest this because the sky will be light enough to get a hand-held photo of the scene. Photos or not, don’t miss what the planets have in store for earthlings this week.

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See All Five Naked Eye Planets in the Dusk Sky at Once

Solar System

Hosting an evening star party this summer? You’re in for a treat. Starting later this week, all five naked eye planets (Mercury, Venus, Mars, Jupiter and Saturn) are visible in the evening sky at dusk for a brief few weeks. We had a similar lineup in the dawn sky earlier in 2016, as the Earth had all the inner planets in its forward-facing view — now, we see these same planets in our collective rear view mirror, as we lap Mars, Jupiter and Saturn on the inner track, while Mercury and Venus race to catch up with us.

At their narrowest, the planets from Saturn to Mercury fit within a span just 75 degrees wide in the last half of August. A wide field all-sky shot should catch ’em all in the same frame at once. This isn’t a ‘grand conjunction’ in a strict sense. To have all five planets visible, you need the slowest and outermost of the five — Jupiter and Saturn, with orbital periods of 11.9 and 29.5 years respectively — in the same general swath of sky. Both are headed towards conjunction on December 21st, 2020, making such groupings more frequent as they race past the other three. The next true quintuple grand conjunction occurs on September 8th, 2040, when all 5 planets span just 9.3 degrees of the sky… the closest span since September 18th, 1186!

There’s  a lot to watch out for in the next few weeks. Here’s a who’s who of planets this July in August, from east to west:

Saturn: shining at magnitude +0.4 in the constellation Ophiuchus, Saturn is fresh off of opposition on June 3rd. Riding high in the southeast at dawn, Saturn makes a close 4.4 degree pass near Mars on August 24th, and the pair makes a straight line completed by the bright star Antares on the same date.

Mars: High to the south in the constellation Libra at dusk, Mars begins its slow dive into the dusk during the last half of 2016. Currently shining at a respectable magnitude -0.9, Mars passed opposition on May 22nd and is headed towards a grand opposition in 2018, nearly as close as the historic close pass of 2003.

Jupiter: Sitting in the constellation Leo, Jupiter shines at magnitude -1.6 and is about 20-30 degrees above the southwestern horizon at dusk. Jupiter passed quadrature 90 degrees east of the Sun on June 4th and opposition for 2016 on March 8th.

Venus: The bashful planet of the group, Venus is slowly appearing from behind the Sun low in the dusk and headed for a brilliant dusk apparition later in 2016 and early 2017. Currently 3 degrees east of the Sun on July 31st, Venus reaches greatest elongation 47 degrees east of the Sun on January 12th, 2017. We’ve just been able to begin spying Venus using binocs last week from the rooftop of our Casablanca Air BnB. Follow that planet, as Venus makes a close 6′ pass near Jupiter on August 27th.

Mercury: And the innermost planet makes five, as Mercury reaches greatest elongation 27 degrees east of the Sun on August 16th. When can you first catch sight of Mercury, completing the fivesome? Jupiter and Venus actually make great bookends in the hunt, as +0.5 magnitude Mercury wanders between them through early August. It’s too bad dusk twilight obscured the view this past weekend, as both Mercury and Venus photobombed the Beehive Cluster M44 in Cancer. Mercury also passes 20′ from the bright star Regulus on July 30th.

But wait, there’s more. The Moon passes New on August 2nd, entering back into the dusk sky. The one day old Moon will pass the grouping of Venus, Regulus and Mercury on the evening of August 4th, actually occulting (passing in front of) Mercury for the southernmost tip of South America. The Moon then moves on to occult Jupiter for good measure on August 6th for the South Pacific and southeast Asia in the daytime. Finally, the waxing gibbous Moon makes a wide pass near Mars, Antares and Saturn on the evening of August 12th, on the same evening that the 2016 Perseids are due to occur.

The Moon also reaches the nearest apogee (think ‘closest far point’) of the year, at 404,265 kilometers from the Earth on August 10th and reaches Full on August 18th, featuring a subtle penumbral eclipse and the start of eclipse season 2 of 2 for 2016.

More on all of these events in the coming weeks. So, if you find yourself out hunting Pokémon G0 creatures ’til the late dusk hours this summer, don’t forget to look up at the greatest show in the solar system!

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Stunning Conjunction of Mars and Beta Scorpii This Week

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Planets can sneak up on you. Especially the ones that don’t rise till you’re in bed. Take Mars for instance. It’s been ambling east along the morning zodiac all winter long; today it enters Scorpius, rising around 1:30 a.m. Not two days later, the planet will have a spectacularly close conjunction with Beta Scorpii, the topmost star in the scorpion’s head.

Also known as Graffias, Beta shines at magnitude +2.6  next to the fiery, zero-magnitude Mars. With their striking color contrast, the two would make a superb ring setting: a tiny diamond nestled next to a plump garnet. They’ll be together for several mornings, their separation changing each day: 15 arc minutes on Tuesday (1/2 the diameter of the Full Moon); 9 arc minutes when closest on Wednesday and back out to 23 minutes on Thursday.

It’s a gas to see two celestial objects approach so closely, but this conjunction offers a rare treat. Did you know that Beta is one of the finest double stars in the sky? It has a fifth magnitude companion 14 arc seconds northeast of the primary. Any telescope will split this jewel and show Mars in the same field of view at both high and low magnifications. That’s just so cool — I sure hope you’ll get to see them.

Mars now measures 10 arc seconds in diameter, small for sure, but big enough to see the larger dark markings and a hint of the north polar cap. The planet is heading for opposition on May 22nd, when it will shine at magnitude -2.0 (brighter than Sirius) with a disk 18.4 arc seconds across, its biggest and closest since 2005.

Let this week’s lovely conjunction serve as a warm-up to the forthcoming season of Mars.

 

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