Rendezvous of Jupiter and Saturn with Moon tonight

By Dr. S.A. Mohan Krishna Amateur Astronomer

Yesterday, we were privileged to see the closeness of three celestial objects namely Moon, Jupiter and Saturn. Tonight (Aug. 29) too in southeastern direction, one can clearly witness these objects with ease, provided the sky should be absolutely clear. Moon, Jupiter and Saturn can be seen tonight in between two constellations ‘Sagittarius’ and ‘Capricornus’ anytime after 7 pm and will be the best time for astrophotography.

Jupiter is the second brightest planet after Venus. In July, Jupiter came closer to our beloved mother planet Earth and for the entire year, Jupiter 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.’ Jupiter stood 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 7 pm and morning 6 am. It reaches the highest point or pinnacle in the sky at around midnight local time. Generally, Jupiter reaches opposition about every 13 months and the distance between Jupiter and Earth in August will be around 642 million kilometres.

Analogously, on July 20, Saturn had rendezvous with Earth and was recommended as 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. Saturn’s rings are well-known and were explored in great detail by the Voyager and Cassini missions. Saturn reached “opposition” on July 20, 2020 and so it will have the best visibility in July and August. Throughout the night Saturn is discernible and more resplendent. From Mysuru, Saturn will be perceptible between 7.30 pm and 6 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. Jupiter and Saturn have planned to dominate this year captivatingly!

There are two reasons for Jupiter and Saturn’s brilliance. These gas planets are huge and they have a high albedo (reflectivity). Jupiter has 1,331 times the volume of Earth, whereas Saturn has 764 times the Earth’s volume. Jupiter reflects about 52% of the incoming sunlight, while Saturn reflects about 47%. 

In contrast, Moon only reflects about 12% of the incoming sunlight. Unlike the stars, which shine by their own light, Jupiter and Saturn shine by reflecting the light of the Sun. Despite Jupiter residing 4.4 astronomical units (AU) from Earth and Saturn at 9.2 AU from Earth right now, these planets still stand out in Earth’s sky. Saturn’s brilliance also depends on the tilt of its majestic rings. You need a telescope to view the rings, but their inclination affects the planet’s brightness as seen from Earth even when looking with the eye alone. Saturn appears brightest when the rings are inclined at a maximum of 27 degrees toward Earth and dimmest when the rings appear edge-on (0 degrees).

Planets move slowly among the stars, following patterns that repeat over months or years. In August and September, Indians are privileged to witness five planets in the morning sky — Mercury, Venus, Mars, Jupiter and Saturn — to fall in line forming a natural planetary conjunction. Enjoy watching these dominating planets. 

More precisely, Moon will be 2.8 degrees south of Saturn on Aug. 28 and 29. Telescopes for planet watching need sturdy mountings and high-quality optics. One can see to Jupiter and Saturn through telescope easily and none can reveal the glory of it. Most observers use powers of 200x or less, due to unsettled seeing. Also useful are coloured filters, which accentuate specific features on planets. So, do not forget to see to the dancing of Jupiter and Saturn with Moon tonight.