On this date – April 7, 2017 – at 22 UTC (5 p.m. Central Time; translate to your time zone), our planet Earth passes most nearly between the sun and the outer planet Jupiter for this year. Earth’s faster movement places Jupiter opposite the sun. Astronomers call this event an opposition of Jupiter.
Because Jupiter is opposite the sun, it’s now rising in the east around sunset, climbing highest in the sky at midnight and setting in the west around sunrise. It shines more brightly than any star in the evening sky, and is the second-brightest planet, after Venus. But Venus only shines for a short while before sunrise at present while Jupiter stays out all night long. Before dawn now, you might catch them both: Venus blazing low in the east and Jupiter, a bit fainter but still brighter than any star, shining in the west.
Jupiter comes to opposition about every 13 months. That’s how long Earth takes to travel once around the sun relative to Jupiter. As a result – according to our earthly calendars – Jupiter’s opposition comes about a month later each year. Last year – in 2016 – Jupiter’s opposition date was March 8. Next year – in 2018 – it’ll be May 9.
Jupiter’s closest approach to Earth for the year always falls on or near this planet’s opposition date. In 2017, Jupiter comes closest to Earth one day after its opposition date, on April 8, coming to within 414 million miles (666 million km) of Earth.
At this 2017 opposition, Jupiter shines in front of the constellation Virgo the Maiden. The close 1st-magnitude star to Jupiter is Spica, the brightest light in Virgo. However, dazzling Jupiter – a planet in our own solar system, and therefore much closer to us – outshines this star by over 20 times.
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 April night, you might — if you’re fanciful enough — you might imagine bright Jupiter as a tiny sun all night long.
Bottom line: Be sure to look for Jupiter on the nights of April 7, 2017 as this world reaches opposition point, the point opposite the sun in our sky. A day later, on April 8, Jupiter reaches its closest point to Earth for this year!