Jupiter, Saturn to be in a ‘great conjunction’


Conjunctions between Saturn and Jupiter occur every 20 years or so but the distance betwen them as seen from Earth varies.

Hyderabad: After four centuries, Jupiter and Saturn would be in a ‘great conjunction’, as seen from the Earth on Monday. Both the planets are bright, and can be easily spotted with the naked eye.

During a great conjunction, celestial bodies appear to be very close to each other to an observer from Earth, though they may actually crores of kilometres apart in space.

Jupiter and Saturn will appear separated by the distance of a coin held at arm’s length, after sunset on December 21 which is also winter solistice — the shortest day and longest night of the year in the northern hemishpere.

Conjunctions between Saturn and Jupiter occur every 20 years or so but the distance betwen them as seen from Earth varies. Given their different orbits round the sun, the one on Monday will appear to be the closest the planets have come in about 400 years. The last time there was such a close encounter was on July 16, 1623. The next such great conjunction will occur on March 15, 2080.

N. Raghunandan Kumar of the Planetary Society of India said the close encounter can be seen for an hour in the western sky after sunset, between 6.15 pm and 7.30 pm. Both of these planets will set by 8.02 pm.

“They will appear like non-twinkling star-like objects to the naked eye. To find them, one has to look westwards, half an hour after sunset, at around 6.20 pm. The brighter planet is Jupiter and the other one is Saturn,” said Raghunandan.

While they will appear to be very close to each other, in reality they will be very far apart: 73,31,37,000 km (73.31 crore kilometres) or 4.9 Angstrom Units (AU) to be exact. One AU is roughly the distance between the Earth and the Sun or about 15 crore kilometres.

“Though these planets appear to be near each other, they are separated by enormous distances among themselves and from Earth,” Raghunandan stressed. On Monday, the distance between Earth and Jupiter is 5.9 AUs (88,41,23,415 or 88.41 crore km) and the distance between Earth and Saturn 10.82 AU (161,86,48,961 or 161.86 crore km).

An added bonus this time would be that the celestial event can be viewed from the Birla Observatory in the city. “During the lockdown, we weren’t allowed to have viewings in a confined space. This time we can see it in the Birla Observstory,” Dr B.G. Sidharth, director, B.M. Birla Science Centre, told Deccan Chronicle.

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