Now is the Time to Observe Jupiter


Photo Credit: NASA/JPL CASSINI Space probe:

Those with telescopes and binoculars, NOW is the time to observe the first of the gas giants and the 1st Jovian planet; Jupiter as it reaches opposition on Tuesday, March 8, 2016 at 11:00 UTC (06:00 EST). This is your best chance to see Jupiter until it reaches opposition again on April 7, 2017 (About 400 days or 13 month cycles).

Jupiter will be primed for observing from now (actually early Feb) through April. At opposition Jupiter will be approximately 4.5 AU from earth (4 times the distance of Earth from the Sun) and will reach an apparent magnitude of -2.6 with a disk of 43.4” arcseconds in size (For example, Mars at opposition only reaches about 15” arcseconds in size and the average Full Moon is just over 2000” arcseconds). If you have a pair of binoculars you can even make out the 4 tiny Galilean moons.

Opposition, in planetary terms is when a superior (outer) planet, dwarf planet or asteroid reaches a point almost exactly opposite the Sun from Earth’s vantage point so we see its full, bright disk.  Another way to say it is Earth is directly between the Sun and that object.  Opposition also places the object near its closest point that it can get to the Earth in its orbit (perigee). Technically opposition and actual perigee points usually differ from a few hours to a few weeks but again, its close enough for what we’re doing.

You may be asking why opposition doesn’t also equal perigee or that body’s closest point to Earth.  Well, as I said above it pretty much does but you have to remember that orbits are elliptical and two orbits don’t mirror each other so even though a planet may be directly opposite the Sun from us, the elliptical nature of orbits usually means the actual closest points tend to be slightly before or after opposition.

You may also be asking why oppositions have different distances opposition to opposition. The reason is the same as the above paragraph, the orbits of the planets aren’t actually circular they’re slightly elliptical. For example, Mars reaches perigee (closest point to Earth) around the same time it reaches perihelion (closest point to the Sun) every 15 to 17 years.  So if Mars reaches opposition at its furthest point from the Sun it will be a more distant opposition than if it were at its closest point to the Sun.  Imagine if we happen to be at aphelion (Earth’s farthest point from the Sun) at the same time say, Mars is at its perihelion?  What a great sight that would be!

Also, during the immediate hours of opposition look for a phenomenon known as the Seeliger Effect. You may also know this as “Opposition Surge”, “Opposition Effect” or even “Opposition Spike.” This is a sudden brightening of the planet; or in this case Saturn’s rings just before and just after opposition. You may notice that the disk of the planet doesn’t brighten; just the rings. The brightening is from the sunlight being reflected off the ice crystals in the rings as they are illuminated from almost the same direction in which we are viewing them from. This also happens with other celestial bodies including the Moon when full vs. its other phases but for slightly different reasons that include shadows etc.

Below I’ve listed the important data as well as a bunch of my favorite links to use and abuse as they’re invaluable assets for sky watching and as always, if you have questions, please ask!  I don’t include Planet, Sun or Moon rise and set times because that’s different depending on where exactly you are but the resources are in the links below.


DATE: Tuesday, March 8, 2016.

TIME: 11:00 UTC (06:00 EST).

WHERE IS IT? (Constellation): Leo the Lion.

WHERE IS IT? (Exact RA/Dec J2000): RA 16h 46m 40s / Dec 20°33’15”.

APPARENT MAGNITUDE: A very bright -2.6.

APPARENT DIMENSIONS (Angular Size): 43.4” arcseconds.

ALTITUDE: About 35 degrees for mid-northern latitudes.

DISTANCE FROM EARTH: 4.5 AU (An AU is 1 Earth/Sun distance or 93 million miles).

OPPOSITION FREQUENCY: Just over a year; 13 months or 400 days.

MOON PHASE: New, 29 days old.

MOON LOCATION: Irrelevant.

Naked Eye Planets Jupiter Location:

Dominic Ford’s “In-The-Sky” page for this event:

In-The-Sky’s, Solar System Body Finder Chart:

U.S. Naval Observatory (USNO) Solar System Body Apparent Dimensions:

U.S. Naval Observatory (USNO) Solar System Body Rise & Set Times:

The Sky Live page for Jupiter:

The Sky Live, Jupiter Tracker:

Chris Peat’s “Heavens-Above” Planet Summary:

The Planets Today (current solar system configuration):

Time and Date Sunrise and Sunset calculator:

Time and Date Moonrise and Moonset calculator:

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