What is the Surface Temperature of Neptune?
June 12, 2017
The surface temperature of Neptune vary from just about -218 °C to -200 °C, making it the coldest Planet within the Solar System.
Our solar system is a fascinating place. Between its eight planets and plenty of dwarf planets, there are some serious variations in terms of orbit, composition, and temperature. Here we will see what is the surface temperature of Neptune.
Whereas conditions inside the inner solar system, where planets are terrestrial in nature, can get pretty hot, planets that orbit on the far side the Frost Line –where it’s cold enough that volatile (i.e. water, ammonia, methane, CO and CO²) condense into solids – will get mighty cold.
Case in point: the surface temperature of Neptune!
While Neptune has no “surface” to talk of, Earth-based analysis and flybys have been conducted that have managed to get correct measurements of the temperature within the planet’s higher atmosphere.
All told, Neptune experiences temperatures that vary from roughly -218 °C to -200 °C, making it the coldest planet within the solar system.
Of all the planets within the solar system, Neptune orbits the Sun at the greatest average distance. With a very minor eccentricity (0.0086), it orbits the Sun at an semi-major axis of roughly 30.11 AU (4,504,450,000,000 km), starting from 29.81 AU (4.459 x 109 km) at point of periapsis and 30.33 AU (4.537 x109 km) at point of apoapsis.
Neptune takes 16 hours 6 minutes and 36 seconds (0.6713 days) to finish one sidereal rotation, and 164.8 Earth years to finish one orbit round the Sun.
This suggests that one day lasts sixty seven as long on Neptune, whereas a year is the equivalent of roughly 60,190 Earth days (or 89,666 Neptunian days).
Because Neptune’s axial tilt (28.32°) is analogous to that of Earth and Mars, (~23° and ~25° respectively), the planet experiences same seasonal changes. Combined with its long orbital period, this implies that the seasons last for forty Earth years.
To boot, the planets axial tilt additionally ends up in variations within the length of its day, moreover as variations in temperature between the northern and southern hemispheres.
Surface Temperature of Neptune:
Due to their composition, deciding a surface temperature of Neptune or any gas or ice giants (compared to terrestrial planets or moons) is technically not possible.
As a result, astronomers have relied on measurements obtained at altitudes wherever the air pressure is adequate to one bar (or one hundred kilo Pascals), the equivalent of atmospheric pressure here on Earth at sea level.
It is here on Neptune, slightly below the higher level clouds that pressures reach between one and five bars (100 – 500 kPa). It’s additionally at this level that temperatures reach their recorded high of -201.15 °C.
At this temperature, conditions are appropriate for methane gas to condense, and clouds of ammonia and hydrogen sulfide are thought to create (which is what provides Neptune its characteristically dark cyan coloring).
But like all gas and ice giants, both deep and surface temperature on Neptune vary as a result of depth and pressure. In short, the deeper one goes into Neptune, the warmer it becomes.
At its core, Neptune reaches temperatures of up to 7000 °C, that is similar to the surface of the Sun. These immense temperature variations between Neptune’s center and its surface produce huge wind storms, which might reach as high as 2,100 km/hour, making them the quickest within the solar system.
Temperature Anomalies and Variations:
Whereas Neptune averages the coldest temperatures within the solar system, a weird anomaly is the planet’s South Pole. Here, it’s ten degrees K hotter than the remainder of planet. This “hot spot” happens because Neptune’s South Pole is presently exposed to the Sun.
As Neptune continues its journey round the Sun, the position of the poles will reverse. Then the northern pole will become the hotter one, and also the South Pole can calm down.
Neptune’s a lot of varied weather in comparison to Uranus is due partially to its higher internal heating, which is especially puzzling for scientists.
Despite the very fact that Neptune is located over five hundred beyond the Sun than Uranus, and receives solely four-hundredth its quantity of daylight, the 2 planets’ surface temperatures are roughly equal.
Deeper within the layers of gas, the temperature rises steady. This is in line with Uranus, however strangely enough, the discrepancy is larger. Uranus solely radiates 1.1 times the maximum amount energy as it receives from the Sun, whereas Neptune radiates about 2.61 times the maximum amount.
Neptune is the farthest planet from the Sun, however its internal energy is enough to drive the quickest planetary winds seen within the solar system. The mechanism for this remains unknown.
And whereas temperatures on Pluto are recorded as reaching lower – all the way down to -240 °C – Pluto’s standing as a dwarf planet mean that it’s not within the same category because the others.
As such, Neptune remains the coldest planet of our Solar System.
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See Also: 8 Facts About Space That Will Shock You!