Today – February 6, 2015 – Earth passes more or less between the sun and Jupiter, placing Jupiter opposite the sun in our sky. Astronomers call this event anopposition of Jupiter. The 2015 opposition is Jupiter’s closest until 2019. 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, and is the second-brightest planet, after Venus. But Venus sets in the west at early evening while Jupiter stays out all night long.
Jupiter blazes away in front of the constellation Cancer. However, Cancer has no bright stars, so the closest 1st-magnitude star to Jupiter is Regulus, the brightest star in the constellation Leo the Lion.
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. For instance, last year – in 2014 – Jupiter’s opposition date was January 5. Next year – in 2016 – it’ll be March 8.
Jupiter’s closest approach to Earth for the year always falls on or near this planet’s opposition date. In 2015, Jupiter comes closest to Earth on its opposition date, coming to within 404 million miles (650 million kilometers) of Earth.
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 and most massive planet in our solar system. So when the sun goes down on this early February 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 February 6, 2015, the night of Jupiter’s opposition. Although the planet shines in front of the constellation Cancer, the brightest nearby star is Regulus, the brightest in the constellation Leo the Lion. This opposition of Jupiter brings Earth’s closest encounter with Jupiter until the year 2019!