Close encounter of Jupiter and Saturn with Earth

By Rtn. PHF Dr. S.A. Mohan Krishna, Amateur Astronomer

This year, people are in a state of utter pandemonium due to ongoing COVID crisis since March. But Astronomy enthusiasts have been active, inquisitive and creative since March. July is the month of many fascinating sky events. Already, comets SWAN and NEOWISE have rejuvenated the minds and reverberated the hearts of millions of people. Yet another good news for astronomy connoisseurs and amateur astronomers! The gas giants, Jupiter and Saturn will have close encounter with Earth on July 14 and July 20 respectively. This will be the best time to see to these planets effortlessly. This astronomical occurrence is called ‘Opposition’.

‘Opposition’ is the astronomical occurrence when a planet farther from the Sun than Earth appears opposite the Sun in the sky. Rightfully, this is the best time to observe a planet. A planet is at opposition when it is directly opposite the Sun from our viewpoint on Earth. This implies, Sun-Earth-planet is in a straight line. This is when the planet is about as close as it can get to Earth, so it is biggest and brightest. Conveniently, the planet rises when the Sun sets and is up all night, setting when the Sun rises. An object is at opposition when the Sun is on one side of the Earth and the object is directly on the opposite side. The result is that the object is fully illuminated by the Sun and appears disk-like. Whenever there is a Full Moon, the Moon is on one side of the Earth and the Sun is on the opposite side.

‘Jupiter’ is the most resplendent bluish-yellow planet in the solar system and is regarded as the biggest planet. In 2019, Jupiter prolonged to dominate the night sky during June, July and August. Jupiter, the monster planet, reached ‘Opposition’ on June 10, 2019. Justifiably, this was the best time to observe a planet. Jupiter, the fifth planet from the Sun, will be at a close opposition, providing an excellent opportunity to observe this planet. On July 14, 2020, Jupiter will be nearest to Earth and could be the brightest celestial object on that day. During planetary opposition, the planet is up entire night and generally closest for the year. ‘Opposition’ is the astronomical occurrence when a planet farther from the Sun than Earth appears opposite the Sun in the sky. Generally, planet Earth flies between the Sun and the gas giant Jupiter.

Jupiter is the 2nd brightest planet after Venus. A few weeks before and after the opposition on July 2020, Jupiter will be very bright, reaching a visual magnitude of about -2.5 to – 2.6. This will be an excellent opportunity to observe Jupiter, its Great Red Spot and Jupiter’s four largest satellites namely Io, Europa, Ganymede and Callisto. These celebrated satellites of Jupiter can be seen in a binocular also. A telescope with a magnification of 40 times or above is preferred in observing Jupiter. The apparent magnitude or brightness factor of Jupiter during July and August is – 2.6. Note that, the negative sign convention indicates that, the brightness will be maximum and for the positive sign convention, the brightness will be minimum. For example, magnitude of Full Moon will be about – 12 and it depicts exceedingly    good resplendence.

In July, Jupiter comes closer to our beloved mother planet Earth for the entire year, and Jupiter, in turn, blazes most brightly in our sky, outshining the night’s brightest stars by leaps and bounds. On July 14, Earth in its orbit swings between the Sun and Jupiter, an event that’s referred to as ‘Opposition of Jupiter.’ At this time, Jupiter stands opposite the Sun in our sky, so it rises in the east at Sunset and sets in the west at Sunrise. Jupiter not only beams at its brilliant best for the year, but stays out all night long! 

From Mysuru, Jupiter will be perceptible between 19:00 to 06:00 or evening 7:00 pm to morning 6:00 am. It reaches the highest point or pinnacle in the sky at around midnight local time. Jupiter can be seen in the vicinity of the constellations ‘Capricornus’ and ‘Sagittarius.’ Generally, Jupiter reaches opposition about every 13 months and the distance between Jupiter and Earth on July 14 shall be 641 million kilometres. 

At around 11.30 pm, Jupiter will reach the highest point in July and this planet stands 20 degrees before the end of twilight. The most interesting aspect during the observation of Jupiter is ‘Great Red Spot.’ This iconic spot has been shrinking over the past several decades and currently spans about 1.3 Earths, but is remains colourful and easy to see at 100x magnification and higher in good seeing. The Great Red Spot maintains its orange-red hue in recent years, a colour shared by the sulphur-encrusted, volcanic satellite of Jupiter Io, the only of the bright satellite of Jupiter to show a distinctive colour.

Analogously, on July 20, Saturn will have rendezvous with Earth and shall be the right time to witness this gorgeous ringed planet. ‘Saturn’ is the sixth planet from the Sun and the outermost planet perfectly noticeable with the unaided eye. The imperative physical distinctiveness like magnitude, composition, internal configuration, and atmosphere advocate an overall similitude to Saturn. Saturn’s rings are well-known and were explored in great detail by the Voyager and Cassini missions. Saturn’s rings has unmitigated, disc-like, effortlessly conspicuous with even a small telescope, which envelops Saturn. Saturn reaches “opposition” on July 20, 2020 and so it has its best visibility this month. On that day, the planet will be closer to earth. Throughout the night Saturn is discernible and    more resplendent.

From Mysuru, Saturn will be perceptible between 19:30 to 06:00 or evening 7:30 pm to morning 6:00 am. It reaches the highest point or pinnacle in the sky at around midnight local time. Saturn can be seen in the vicinity of the constellations ‘Capricornus’ and ‘Sagittarius.’ Saturn appears cream-white in colour and is among the brightest star-like objects in our sky this winter. 

Saturn in 2020 rises earlier and continues to creep higher above the southeastern horizon earlier each night. Saturn was visible in the southeast by 7 pm in early July. 

Do not forget to see to Jupiter and Saturn this month. With the help of telescope and astral binoculars, none can rival the glory of these planets.