Today – January 5, 2014 – Earth passes more or less between the sun and Jupiter, placing Jupiter opposite the sun in our sky. Astronomers call this event an opposition of Jupiter. The 2014 opposition is Jupiter’s closest until 2020. Jupiter rises at sunset, is highest in the sky at midnight and sets at dawn. It shines more brightly than any star in the evening sky. It blazes away in front of the constellation Gemini, near the bright Gemini stars, Castor and Pollux.
The animation at right shows Mercury, Venus, Earth, Mars and Jupiter revolving around the sun. Beyond the orbit of Jupiter, Saturn and Uranus appear in their own respective orbits, too. Earth orbits about 12 times for every single orbit of Jupiter. It’s when Earth passes between the sun and Jupiter that we see Jupiter opposite the sun in our sky.
Jupiter comes to opposition about every 13 months. In other words, that’s how long Earth takes 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 2014, Jupiter came nearest to Earth on yesterday (January 4). Then Jupiter was only 391 million miles (630 million kilometers) away. It’s only slightly farther away tonight.
And, because it’s opposite the sun around now, you can see Jupiter at any time of night. For example – as the chart at the top of this post shows – you can see it in the east at nightfall and early evening. Around midnight, when the sun is below your feet, Jupiter appears high overhead. At dawn tomorrow, you’ll see Jupiter low in your western sky.
Jupiter is sometimes called a failed star. 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 January 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 January 5-6, 2014, the night of Jupiter’s opposition. The planet shines in front of the constellation Gemini, near the bright Gemini stars Castor and Pollux. This opposition of Jupiter brings Earth’s closest encounter with Jupiter until the year 2020!