On 16th September 2022, the outermost planet Neptune will be closest to Earth. Although Neptune is not visible with naked eyes, but as seen with a telescope, on this date it will be at its biggest this year.

The Opposition of Neptune is one day later, falling on 17^th September. The date of closest of Neptune to Earth and its ‘Opposition’ always differs by about a day at its maximum or a few hours at its minimum.

Neptune has many associated adjectives –

The Calculated Planet

Neptune was mathematically predicted before it was directly observed. In 1846, the planet Uranus had completed nearly one full orbit since its discovery by William Herschel in 1781, and astronomers had detected a series of irregularities in its path that could not be entirely explained by Newton’s law of universal gravitation. These irregularities could, however, be resolved if the gravity of a farther, unknown planet were disturbing its path around the Sun. In 1845, astronomers Urbain Le Verrier in Paris and John Couch Adams in Cambridge separately began calculations to determine the nature and position of such a planet. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet were made on the night of September 23–24, 1846, at the Berlin Observatory, by astronomer Johann Gottfried Galle (assisted by Heinrich Louis d’Arrest), working from Le Verrier’s calculations. It was a sensational moment of 19th-century science, and dramatic confirmation of Newtonian gravitational theory.

The Outermost Planet

With Pluto no longer considered a planet but a Dwarf Planet, Neptune becomes the outermost planet. Even otherwise Pluto’s orbit comes inside the orbit of Neptune for some of its part. In 2011 Neptune completed its first 165-year orbit since its discovery in 1846.

The Windy Planet

Neptune is the windiest planet in our solar system, whipping up momentous gusts that can reach 2,000 kilometres an hour, much more than the speed of a jet plane. That soothing sapphire expanse does reveal some of the whirling chaos below in the form of cloudy bands and massive gyres that look like dark smudges on its surface. Neptune rotates quickly compared to Earth, with one day taking 16 Earth hours. But its great distance from the sun means the years are long, requiring 165 Earth years to make one trip around our glowing star.

The Icy Giant

In 1952, science fiction writer James Blish coined the term gas giant and it was used to refer to Jupiter, Saturn, Uranus and Neptune. However, since the late 1940s the compositions of Uranus and Neptune have been understood to be significantly different from those of Jupiter and Saturn. They are primarily composed of elements heavier than hydrogen and helium, constituting a separate type of giant planet altogether. Because during their formation Uranus and Neptune incorporated their material as either ices or gas trapped in water ice, the term ice giant came into use. Neptune and Uranus are now referred to as ice giants. Lacking well defined solid surfaces, they are primarily composed of gases and liquids.

Aperture Telescopes is organising an evening observation on Friday, 16th September at its Astro Facility – Manesar. We will put up several large telescope on our terrace to see the planets.

Prominent attractions of the evening observation –

1. Saturn rises well before sunset this evening. Saturn, its rings and a retinue of moons will be prominent in the sky at this observation. Saturn is located in the constellation of Capricorn.
2. This evening Jupiter will have its Great Red Spot (GRS) side turned towards the Earth. We will be able to see the transit of the Great Red Spot. The opposition of Jupiter is scheduled just 10 days later on (which means that the two planets are about 10 degrees apart). Jupiter’s closest approach to Earth is on 26^th September and Opposition falls on 27^th
3. Uranus rises at about 21:06 and will be visible about 20 minutes later. When Uranus rises, all the Giant Planets will be visible in the sky at the same time.
4. Moon and Mars are close together in the sky and rise at about 22:41, and will be visible by about 23:00.

All are welcome to join the observation.
Learn about the telescopes that we make at Aperture Telescopes.
Observe all the Giant Planets of our Solar System.

Circumstances of the Moon on the night of observation –