Astronomy: Neptune

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Table of Contents

  1. Basic Facts
  2. Atmosphere
  3. For Educators

Facts about Neptune

Here is the end of our trip through the Solar System, we have reached the final planet, Neptune. If you are wondering, Pluto is not considered a planet because it has not cleared all the space debris in its orbit. It is considered a dwarf planet(this is debated often so it may change).

A day on Neptune is about 16 hours, and one year is 165 Earth years.

Neptune is likely similar to Uranus, and it is much larger, 17 times Earth’s mass whereas Uranus is 14.5 times. It is also azure blue, where Uranus is teal green. Neptune also has a lot of methane, but its almost equal to Uranus so the color difference is odd. In the post on Uranus, I explained that it is blue because methane absorbs red light, and only reflects the blue light, so we see it as blue. Since Neptune has nearly equal amounts of methane, it is odd that there is a significant color difference. This is likely caused by other components in the atmosphere, though it could be a variety of different factors.

This first image shows a comparison of Uranus and Neptune, with Neptune on the left. The color difference is very obvious but not well explained.
Here is a nice info graphic from NASA outlining the Hubble Telescope, which has recently stopped operating and is to be replaced with the James Webb Telescope

Neptune has a very active atmosphere, where the winds can reach 2000 km/hr. A storm was seen on the planet by Voyager 2 in 1989 and is known as the Great Dark Spot. However, it dissipated by 1994 when it was observed by Hubble Telescope, and a new one appeared in 2016. So this spot appears to come and go, and it is not known why as far as I understand.
Even though Saturn is the planet known for its rings, it is not the only planet to have them. Neptune does also, it has 3 main rings, 2 of which are thin and one is broad
It has over a dozen moon. The largest of Triton, 2700 km wide and orbits in retrograde motion.

Here is a photo of Neptune’s largest moon, Triton

Atmosphere: The Great Dark Spot

Neptune has a similar atmosphere to Uranus, it is 80% Hydrogen gas, 19% Helium gas, and a little less than 1% Methane. The 1% of Methane accounts for the planet’s blue-green color. This planet has the strongest winds in the whole Solar System. The most unique thing about the planet is the Great Dark Spot, a storm the size of Earth. This was first observed by Voyager 2 spacecraft in 1989, but was determined to have disappeared in 1994 by the Hubble Telescope. The storm has recently reappeared, however, so it is understood to be much like Jupiter’s Great Red Spot except smaller and having a short life span. It also is relatively clear of clouds in the interior.

The dark spot in the middle of the planet is the Great Dark Spot. Because it is such a violent storm, it has immense pressure and caused disturbance among the gases, causing the dark color.

For Educators

Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.

Thank you

Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!