By Jove: Jupiter at Opposition 2017

Jupiter from January 7th, 0217. Image credit and copyright: Fred Locklear.

Been missing the evening planets? Currently, Saturn and Venus rule the dawn, and Mars is sinking into the dusk as it recedes towards the far side of the Sun. The situation has been changing for one planet however, as Jupiter reaches opposition this week.

Jupiter in 2017

Currently in the constellation Virgo near the September equinoctial point where the celestial equator meets the ecliptic in 2017, Jupiter rules the evening skies. Orbiting the Sun once every 11.9 years, Jupiter moves roughly one zodiacal constellation eastward per year, as oppositions for Jupiter occur about once every 399 days.

As the name implies, “opposition” is simply the point at which a planet seems to rise “opposite” to the setting Sun.

At opposition 2017 on Friday, April 7th, Jupiter shines at magnitude -2.5 and is 666.5 million kilometers distant. Jupiter just passed aphelion on February 16th, 2017 at 5.46 AU 846 million kilometers from the Sun, making this and recent oppositions slightly less favorable. An April opposition for Jupiter also means it’ll now start to occur in the southern hemisphere for this and the next several years. Jupiter crosses the celestial equator northward again in 2022.

The path of Jupiter through 2017. Image credit: Starry Night.

Can you see Ganymede with the naked eye? Shining at magnitude +4.6, the moon lies just on the edge of naked eye visibility from a dark sky site… the problem is, the moon never strays more than 5′ from the dazzling limb of Jupiter. Here’s a fun and easy experiment: attempt to spot Ganymede through this month’s opposition season, using nothing more than a pair of MK-1 eyeballs. Then at the end of the month, check an ephemeris for greatest elongations of the moon. Any matches?

With binoculars, the first thing you’ll notice is the four bright Galilean moons of Io, Europa, Ganymede and Callisto. At about 10x magnification or so, Jupiter will begin to resolve as a disk. With binoculars, you get a very similar view of Jupiter as Galileo had with his primitive spy glass.

At the telescope eyepiece at low power you can see the main cloud bands of Jove, the northern and southern equatorial belts. Shadow transits and eclipses of the Jovian moons are also fun to watch, and frequent for the innermost two moons Io and Europa.  Orbiting Jupiter once every seven days, transits of Ganymede are less frequent, and outermost Callisto is the only moon that can “miss” Jupiter on occasion, as it does this year until transits resume in 2020.

Jupiter an the Great Red Spot from January 29th, 2017. Image credit and copyright: Efrain Morales.

Jupiter’s one of the best planets for imaging: unlike Venus or bashful Mars, things are actually happening on the cloudtops of Jove. You can see smaller storms come and go as the Great Red Spot make its circuit once every 10 hours. Follow Jupiter from sunset through sunrise, and it will rotate just about all the way around once. Strange to think, we’ve been using modified webcams to image Jupiter for over a decade and a half now.

Jupiter and Io from 2006. Photo by author.

The major moons of Jupiter cast shadows nearly straight back as seen from our vantage point near opposition. After opposition, the shadows of the moons and the planet itself begin to slide to one side and will continue to do so as the planet heads towards quadrature 90 degrees east of the Sun. In 2017, quadrature for Jupiter occurs on July 5th as the planet sits due south for northern hemisphere observers at sunset. Distances to Jupiter vary through opposition, quadrature and solar conjunction, and Danish astronomer Ole Rømer used discrepancies in predictions versus actual observed phenomena of Jupiter’s moons to make the first good estimation of the speed of light in 1676.

Double shadow transits are also interesting to watch, and a season of double events involving Io and Europa begins next month on May 12th.

Jupiter will rule the dusk skies until solar conjunction on October 26th, 2017.

It’s also interesting to note that while the Northern Equatorial Belt has been permanent over the last few centuries of telescopic observation, the Southern Equatorial Belt seems to pull a disappearing act roughly every decade or so. This last occurred in 2010, and we might just be due again over the next few years. The Great Red Spot has also looked a little more pale and salmon over the last few years, and may vanish altogether this century.

Finally, the Full Moon typically sits near a given planet near opposition, as occurs next week on the evening of April 10/11th.

Jupiter, the Moon and Spica on the evening of April 10th. Credit: Stellarium.

The next occultation of Jupiter by the Moon occurs on October 31st, 2019.

Don’t miss a chance to observe the king of the planets in 2017.

– Here’s a handy JoveMoons for Android and Iphone for planning your next Jovian observing session.

-Be sure to check out our complete guide to oppositions, elongations, occultations and more with our 101 Astronomical Events for 2017, a free e-book from Universe Today.

-Send those images of Jupiter in to Universe Today’s Flickr forum.

Watch: An Amazing, Mesmerizing Full Rotation of Jupiter

Jupiter as imaged by Michael Phillips on July 25th, 2009... note the impact scar discovered by Anthony Wesley to the lower left.

Jupiter is a happening place in the solar system. While bashful Mars only puts on a good show once every two year opposition period, and inner worlds such as Mercury and Venus yield no surface details to backyard observers at all, the cloud tops of Jupiter display a wealth of changing detail in even modest backyard telescopes.

And this month is a great time to start observing Jupiter, as the largest planet in our solar system just passed opposition on January 5th. Recently, veteran astrophotographer Michael Phillips amazed us here at Universe Today once again with a stunning time-lapse sequence of Jupiter and its moons Ganymede and Io. Now, he’s outdone himself with a new full rotation compilation of the gas giant planet.

The capture is simply mesmerizing to sit and watch. At 9.9 hours, Jupiter has the fastest rotational period of any planet in our solar system. In fact, with Jupiter currently visible low to the east at sunset, it’s possible to follow it through one rotation in the span of a single long January winter night.

We caught up with Michael recently and asked him about this amazing capture. The sequence was actually accomplished over the span of five successive evenings. This made it challenging to stitch together using a sophisticated program known as WINJupos.

“While this is possible on a long winter night when it is darker longer, I typically find it easier to do over multiple nights than one long sleepless night,” Michael told Universe Today. “If you wait too many days between observations, the features will change significantly, and then two nights will not match up clearly. The seams that result from using multiple nights are tricky to stick together. I created multiple non-overlapping seams and tried to blend them out against one another as layers in my image editing software. The result is smoother, but not quite the same as a single observation.”

A 14” f/4.5 Newtonian reflecting telescope was used for the captures. “Similar weather conditions and camera settings help quite a bit to make the multiple nights’ segments match up better,” Michael noted. “Keeping the same settings, using the same location away from my house  in the corner of the yard (to reduce local atmospheric turbulence) night after night gives consistent results after removing the variability of the weather.”

Planetary photography also requires special considerations prior to imaging, such as getting Jupiter high enough in the sky and at specific longitudes to get full coverage in the rotation sequence.

“I try to consider the local weather patterns and atmospheric stability (seeing), but in reality, I pushed myself to get out as much and often as I could,” Michael told Universe Today. “Typically, I try to wait until Jupiter is at the highest in the sky, as the result is looking through less atmosphere and thus more stable conditions. Sometimes, the planets jiggle around and you just want to scream ‘SIT STILL!’ Basically around the time of opposition I go out as often as it’s clear, as those are opportunities that you don’t get back again until next year.”

Jupiter reaches opposition just over once every 13 months, moving roughly one constellation eastward each time. 2013 was an “oppositionless” year for Jupiter, which won’t occur again until 2025. Michael also notes that from his observing location at 35 degrees north latitude, Jupiter currently peaks at an altitude of 77 degrees above the horizon when it transits the local meridian. “I wasn’t going to squander it waiting for perfect conditions!”

In fact, Jupiter is currently in a region in the astronomical constellation of Gemini that will be occupied by the Sun in just over five months time during the June Solstice. Currently at a declination of around 22 degrees 45’ north, Jupiter won’t appear this high in the northern sky near opposition again until 2026.

It’s also amazing to consider the kind of results that backyard observers like Michael Phillips are now routinely accomplishing. It’s an interesting exercise to compare Michael’s capture side-by-side with a sequence captured  by NASA’s New Horizons spacecraft during its 2006 flyby of Jupiter:

Both sequences capture a wealth of detail, including the enormous Great Red Spot, the Northern and Southern Equatorial Belts, and numerous white spots and smaller swirls and eddies in the Jovian atmosphere.

To date, six spacecraft (Pioneer 10 and 11, Voyagers 1 and 2, New Horizons and Cassini) have made flybys of Jupiter, and one, Galileo, orbited the planet until its demise in 2003. Juno is the next in this legacy, and will be inserted into orbit around Jupiter in July 2016.

Now is the time to get out and observe and image Jupiter and its moons, as it moves higher into the sky on successive evenings towards eastern quadrature on April 1st, 2014.

Congrats to Michael Phillips on an amazing sequence!