What is the Opposition?
In our Solar System planets are usually divided into two groups — the inner and outer planets. According to classical astronomy theory, the inner planets are Venus and Mercury. Their orbits pass inside the orbit of the Earth, so this is the reason why they are called the inner planets.
However, the outer planets (Mars, Jupiter, Saturn, Uranus and Neptune) can appear in the opposite part of the sky, far away from the Sun. In other words, celestial longitude or elongation of the planet differs by 180° from the longitude of the Sun. The outer planet reaches this position halfway through a retrograde. This phenomenon is called the “opposition” of a planet and happens when the planet and the Sun are on opposite sides of the celestial sphere, as observed from Earth.
A planet at opposition rises just after sunset and can be seen in the sky all night long. This is the time when a planet is closer to Earth than usual. That is why in our sky it looks brighter and larger. During oppositions you will have the best chance to observe the outer planets of our Solar System.
When will we see Jupiter in the sky?
Jupiter is always bright — it’s the largest planet in our solar system. It shines more brightly than any star in the evening sky. At this 2020 opposition, Jupiter shines close to the planet Saturn, in front of the constellation Sagittarius. There’s no way to mistake Saturn for Jupiter, though, because dazzling Jupiter outshines this 1st-magnitude star by some 14 times. With the exception of the Sun and the Moon, only Venus — the brightest planet, now low in the east before sunrise — outshines Jupiter.
Jupiter reaches opposition on July 14, 2020, at about 08:00 GMT (4:00 EDT), and comes closest to Earth on July 15, 2020, at about 10:00 GMT (6:00 EDT). To become a witness of this unique and beautiful phenomenon for your location, you can use our Star Walk 2 app. It will allow you to take a closer look at Jupiter at its travel through the universe.
How frequent Jupiter’s Opposition is?
Jupiter comes to opposition roughly about every 13 months. This is how long Earth takes to travel once around the Sun relative to Jupiter. As a result, Jupiter comes a month later every year. Last year, 2019 the date of opposition was June 10 and if you miss this year’s opposition, don’t worry! Thirteen months later Jupiter’s opposition will happen again — in 2021 it’ll be August 19.
Pluto reaches Opposition along with Jupiter
Pluto will reach an opposition just around middle July — on July 15. It is pretty rare to witness these two planets at oppositions almost together! Though, keep in mind that to actually see Pluto in the sky, you’ll need a telescope with at least an 8-inch diameter mirror or, which is way easier, download Star Walk 2 and enjoy it whenever you want.
As was mentioned, on a midway point of a retrograde happens what we call an opposition. However, since Pluto belongs much further from the Sun than Jupiter does, Pluto’s retrograde lasts nearly six weeks longer than Jupiter’s four-month retrograde.
Here is a simple comparison: Jupiter begins retrograde on May 14, 2020 and ends it on September 13, 2020. The opposition date is July 14, 2020. Pluto’s opposition date is July 15, 2020, but it begins its retrograde on April 25, 2020 and ends on October 4, 2020.
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