This is How Cold The Surface of Neptune Really is, And What Could Survive There

Written by Jeremiah Wright
Updated: October 10, 2022
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Neptune is known as a giant planet. It is the fourth-largest in diameter and the third-largest in terms of mass in the Solar System. Neptune is also the densest – its mass is 17 times the mass of our planet. The planet is the eighth planet from the Sun and primarily consists of liquids (ammonia, water) and gasses (hydrogen, helium, nitrogen, and hydrocarbons). As a result, Neptune doesn’t really have a defined solid surface.

Unlike its twin (Uranus), Neptune is known for having weather patterns identified as Great Dark Spots. At the same time, the planet has the strongest winds in the Solar System that reach approximately 1,300 mph.

Pertinent to our topic today is the fact that Neptune is quite far from the Sun. As such, it is one of the coldest planets around. Let’s see exactly how cold the planet’s surface is and what could survive there!

How cold is the surface of Neptune really?

Abstract Neptune planet generated texture background

According to NASA, the mean temperature of Neptune is -330 °F.


The average temperature of Neptune’s surface is about -373 °F. However, just like Uranus, this planet is surrounded by cold clouds and lacks a solid surface. Within these clouds, temperatures vary from -240 °F to -330 °F. Add 150 °F, and the planet’s temperature would reach absolute zero – a state where molecular motion stops entirely.

These low temperatures are partly attributed to the fast winds roaming this planet’s gaseous surface. Neptune winds can blow with speeds of up to 1,300 mph. Even the planet’s equatorial regions don’t slow down in terms of wind speed – about 700 mph. This makes for an extremely cold planet.

Neptune is so cold that even one of his satellites has the coldest temperature in the Solar System. Triton’s weather, if it can be called that way, stands at -391 °F.

According to NASA, the mean temperature of Neptune is -330 °F (for this planet, the mean temperature was recorded at an atmospheric pressure level equal to Earth’s pressure at sea level).

What could survive on Neptune?

Planet neptune

No organism could survive on Neptune – unless in a cryogenic state.

© bhaumik

Average temperatures on Neptune are less than -100 °F from absolute zero, a point where all molecular motion stops. As such, no organism could survive on Neptune – unless in a cryogenic state.

Organisms that could endure extremely low temperatures do exist. They are known as cryophiles and can be insects, fungi, lichens, bacteria, phytoplankton, and certain snow algae. However, these are known to undergo the process of vitrification once temperatures drop below -13 °F. The process doesn’t kill them, an aspect that might make you think they could live on Neptune. But the truth is they can’t!

Vitrification turns these organisms into glass-like bodies. Molecules inside them are still active but cannot live, grow, develop, and evolve as they should. This state can be compared to a cryogenic state. Therefore, organisms can, at most, be active on the surface of Neptune. Temperatures of -373 °F are ideal only for long-term organism preservation. 

When pairing the extremely low temperatures with the other harsh conditions on Neptune, such as the impressive wind speeds, it is clear that no organism could survive there. It is, after all, one of the coldest planets in our Solar System.

Could tomato plants or other vegetables/fruits survive on the surface of Neptune?

Tomatoes, other vegetables, and fruits couldn’t survive the freezing surface of Neptune. Some plants can live in chilly environments, while most of them can overcome some frost – none can actually endure prolonged freezing temperatures.

Given that Neptune’s surface temperature is -373 °F, it goes without saying that no plants could survive on its surface. The fact that the planet is made primarily of liquids and has no solid surface doesn’t help plants survive.

Could tardigrades survive on the surface of Neptune?

Tardigrades are highly resilient microscopic animals that can be found all over Earth. They have survived being exposed to outer space, and it is believed they can also survive the apocalypse. But could they survive the surface of Neptune?

These animals are comfortable at temperatures up to 98 °F (and above freezing). In this temperature range, tardigrades are in their active state. They also have something called a tun state, which is aimed more at preserving the tardigrade until temperatures return to normal. In the tun state, these tiny animals can survive temperatures as high as 300 °F and as low as -328 °F.

Given the temperatures on the surface of Neptune, tardigrades couldn’t survive there at all – maybe just for a couple of hours. Eventually, they’d freeze to death.

Would water be frozen or liquid on the surface of Neptune?

Water would be rock-solid frozen on the surface of Neptune. After it freezes at 32 °F, the water molecules inside the freshly made ice get denser and denser. The water volume decreases at the same time. Ultimately, at extremely low temperatures, the water turns into ice that is as tough as rock. As a result, pure water on the surface of Neptune would probably mean a solid surface for this liquid giant.

It is worth mentioning that scientists are trying to keep water liquid at temperatures well below its freezing point. This aspect could have various applications in the future. At the moment, scientists are able to keep water in a liquid state at temperatures as low as -49 °F – quite a lot below its freezing point. It is possible that, in the future, liquid water on Neptune’s surface won’t sound as crazy as it does now.

Are there any signs of life on Neptune?

Neptune is incompatible with any form of life that we know.


Neptune is the farthest planet from the Sun. The planet’s surface is mostly dark, extremely cold, and features winds that would destroy any plant or living organism. These aspects make it incompatible with any form of life that we know.

However, some studies explore the possibility that the gas giants in our Solar System (one of which is Neptune) could shelter oceans beneath their gas layers.

The main characteristics of Neptune

VolumeMassSurface gravityAverage surface temperaturePredominant composition element
Neptune57.74 Earths17.147 Earths1.14 g-373 °FHydrogen (80%)
Earth2.59876×1011 cu mi1.31668×1025 lb1 g / 32.1740 ft/s257 °FNitrogen (78.08%)

How long is a one-way trip to Neptune?

A one-way trip to Neptune is about 12 years long. This value takes into account the trip of Voyager 2; a spacecraft sent into space in 1977. It is possible that modern spacecraft could make the same trip in a shorter amount of time, but this hasn’t been officially confirmed yet.

Voyager 2 is the only spacecraft to have visited Neptune and its neighbor, Uranus. Several years after the spacecraft had reached Uranus, it visited Neptune as well. 

7 interesting facts about Neptune

Want to know more about Neptune? Here are seven interesting facts that will certainly grab your attention:

  • If we do not consider Pluto a planet, then Neptune is the farthest planet from the center of our Solar System.
  • Neptune’s largest moon, Triton, is considered a captive of this planet. Unlike other moons, Triton has a retrograde orbit, which means it spins in an opposite direction of Neptune’s rotation. 
  • Neptune has five rings, although they are difficult to see. These rings consist of dust (between 20 and 70%) which is measured in micrometers. 
  • Neptune is the coldest planet in our Solar System, with mean temperatures of -330 °F. Its temperature is very close to absolute zero – one of the main reasons why life cannot survive there.
  • Neptune has the strongest winds in the Solar System – up to 1,300 mph. This partly contributes to the low temperatures, but this also baffles scientists. In theory, a planet this cold shouldn’t have such fast winds.
  • Neptune’s gravity is the closest to Earth’s gravity among all planets in the Solar System. This planet’s gravity is about 110% of Earth’s gravity.
  • Neptune was first seen in the sky by Galileo Galilei, who marked it as a star. This is why the planet’s discovery is attributed to Heinrich d’Arrest and Johann Galle. They discovered the planet two centuries later, based on a prediction by Urbain le Verrier.

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The photo featured at the top of this post is © bhaumik

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About the Author

I hold seven years of professional experience in the content world, focusing on nature, and wildlife. Asides from writing, I enjoy surfing the internet and listening to music.

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