Jupiter calling : Don’t miss its biggest, brightest show

Known as the opposition of Jupiter, the planet can be seen in the constellation Libra and will be visible all night

This April 3, 2017 file image made available by NASA shows the planet Jupiter when it was at a distance of about 668 million kilometers from Earth.

At 05:40 hours IST on May 9, 2018, stargazers will be able see Jupiter at its brightest, and it will also appear bigger than usual.

Known as the opposition of Jupiter, the planet can be seen in the constellation Libra and will be visible all night, reaching its highest point in the sky at around midnight local time.

Two astronomical objects are in opposition when they are on opposite sides of Earth. A planet is in opposition when it is on one side of Earth and the Sun is on the other.

Several interesting phenomena occur at opposition

The distance between Jupiter and Earth during their revolutions varies roughly from 4.2 to 6.2 AU (1 astronomical unit equals about 150 million km). During opposition, the planet appears bigger and brighter as it is at the closest point to Earth.

“You can spot Jupiter easily in the East, as it will be the brightest object in the sky one hour after the sun sets. Even at its closest approach to the Earth, it will be a star-like point of light to the naked eye, though a good pair of binoculars is sufficient to reveal it as a disk of light with accompanying system of Moons,” says Ajay Talwar, an astrophotographer and the India Representative in The World At Night (TWAN), a project that features images of the night sky.

The disk of the planet will measure 43.8 arc second in diameter. (1 arc second is 1/60 of arc minute and 1 Arc minute is 1/60 of a degree in the sky. For reference, the diameter of Moon is about 31 minutes of arc).

The shining of the planet will be at magnitude -2.5. The lesser the value (higher numbers in the negative), the brighter the object. As a handy reference, the brightness of a full moon is -12 and the brightest planet Venus is -4.

Earth overtaking Jupiter

“Earth being an inner planet goes faster in its orbit and it seems like it is overtaking Jupiter. Although Jupiter is going in the same direction, it seems like it is moving in the opposite direction. Similar to a car overtaking another on a highway. If you are sitting in the faster car, it seems that the other car is apparently moving in the other direction. This apparent planet motion is called Retrograde Motion,” said Mr. Talwar.

Here is a video of last year’s Jupiter Opposition from NASA