Keep an Eye out for Jupiter 12/2-3

Earth passes between Jupiter and sun on December 2-3, 2012


Tonight for December 2, 2012

Moon Phase Courtesy U.S. Naval Observatory

This animation shows Mercury, Venus, Earth, Mars and Jupiter making one full revolution. Saturn and Uranus also appear in their own respective orbits around the sun. Earth orbits about 12 times for every single orbit of Jupiter. When Earth passes between the sun and Jupiter, we see Jupiter opposite the sun in our sky. We call that an opposition of Jupiter.

Today Earth passes between the sun and Jupiter, placing Jupiter opposite the sun in our sky. Astronomers call this event an opposition of Jupiter. The 2012 opposition is Jupiter’s closest until 2021. Jupiter shines more brightly than any star in the night sky. It is in a region of the sky filled with bright stars, near the bright star Aldebaran in the constellation Taurus.

Taurus? Here’s your constellation.

The clocks in Austin, Texas, say the opposition is tonight at 8 p.m. on December 2. Yet, according to Universal Time – the standard clock time at the meridian of 0o longitude – the opposition of Jupiter happens at 2 a.m. on December 3. The opposition happens at the same instant worldwide but at different clock times.

For the fun of it, we also show the asteroid Vesta’s place in front of the constellation Taurus on the feature chart at top, because this world will be at opposition and closest to Earth on December 9, 2012. More than likely, you’ll need an optical aid, a dark sky and a good sky chart to see Vesta. The moonless nights accompanying the Geminid meteor shower on December 12, 13 and 14 should be great spotting the asteroid Vesta (possibly even with the unaided eye).

How do I translate Universal time into my time?

One thousand Earths could fit inside Jupiter. Image credit: NASA

But for now, we return our focus on Jupiter, the largest world in our solar system. It shines well over four thousand times more brightly than the asteroid Vesta.

Jupiter comes to opposition every 13 months or so, as Earth takes this long to travel once around the sun relative to Jupiter. Jupiter’s closest approach to Earth for the year always falls on or near this planet’s opposition date. In 2012, Jupiter came nearest to Earth on December 1, at 15 hours Universal Time (9 a.m. Central Time). Then Jupiter was only 378 million miles (609 million kilometers) away. Because Jupiter passed its perihelion – or closest point to the sun – in March 2011, the giant planet is now getting farther from the sun. As a result, at this opposition, Jupiter is as close as it will be until the year 2021.

And, because it’s opposite the sun around now, you can see Jupiter at any time of night. For example – as today’s chart shows – you can see it in the south at midnight tonight, when the sun is below your feet. At dawn tomorrow, you’ll see Jupiter low in your western sky. At opposition, Jupiter shines at its brightest in our sky.

Earth and Jupiter closer on December 1, 2012 than until 2021

Jupiter is bright! It will be shining more brightly than any of the surrounding stars. This photo of Jupiter is from November 18, 2012. It’s from EarthSky Facebook friend Carlos Colon Sr.

You would need at least 80 Jupiters — rolled into a ball — to be hot enough inside for thermonuclear reactions to ignite. In other words, Jupiter is not massive enough to shine as stars do. But Jupiter is the largest planet in our solar system. So when the sun goes down on this early December night, you might — if you’re fanciful enough — imagine bright Jupiter as a tiny sun all night long.

Bottom line: Be sure to look for Jupiter on the night of December 2-3, 2012, the night of Jupiter’s opposition. The planet shines in front of the constellation Taurus, very near the brightest star in Taurus, Aldebaran. This opposition of Jupiter brings Earth’s closest encounter with Jupiter until the year 2021!