Space

Do other planets have weather?

Short Answer: Yes!

More Interesting Answer: Read on…

On Earth, the weather is powered by the interaction between the sun, rotation of the earth, and our atmosphere. The energy from the sun heats up water on the surface, causing it to evaporate, which causes rainfall. And the energy from the sun is what drives the winds that carry the rain around the globe. So technically, any planet can have weather, as long as it has an atmosphere, as weather is simply the state of the atmosphere, caused by an imbalance in energy. And this is proven when we look out into the solar system!


For future reference, here’s a quick fact file of some of Earth’s average, and record, weather phenomena! 

Temperature
Hottest: 56.7°C, Death Valley (although there have been unverified claims of temperatures up to 70°C!)
Average: 15°C
Coldest: -89.2°C, Antarctica
Wind Speed
Fastest: 254mph

Planetary Weather has been observed since the advent of the telescope in the 1600s, famously through the discovery of Jupiter’s Great Red Spot… maybe. Observation of a ‘Permanent Spot’ in Jupiter’s atmosphere was recorded all the way back in 1665, but it is unknown if this is the same one we see today. Today, Jupiter’s Great Red Spot is shrinking, but it is still bigger than Earth! Not only is it huge in diameter, the winds reach speeds of up to 400mph, and its clouds tower 8km above the surrounding clouds, which is because it is colder than the rest of the atmosphere. Despite featuring in many images from both spacecraft and ground-based telescopes, it is still quite the mystery, but is our first clue to understanding the huge scale of space weather! 

Hubble Spots Jupiter's Great Red Spot | NASA

The great red spot is bound between two of the jets of wind that make up Jupiter’s iconic striped pattern, which are similar to those found on many of the gas giants, but also to some extent, earth! On Earth we have a system of 6 cells, bands of winds parallel to the equator that govern the direction that storms and ships travel! Saturn shares this banded system of winds, but around the north pole, the bands have taken on a strangely symmetrical hexagonal shape. There are two interesting things about this cloud pattern: 

  1. It might be part of a system that goes deep beneath the superficial top layer that is seen across most of the planet. Most of Saturn’s atmosphere is not only split into bands, but also layers, but this system appears to be one tall structure, as we have observed identical patterns at both the superficial altitude and a lower altitude! 
  2. It has changed colour in the space of less than a decade, showing the variability of the weather despite being on such a large scale. One theory to explain this puts it down to the changing seasons (which occur on a longer time frame than Earth’s due to the distance from the sun) exposing the North Pole to the sun, and increased radiation, which causes changes in the composition of the atmosphere through creating a haze. 

Orbiting Saturn is Titan, which has the thickest atmosphere of any non-planetary body (it’s even thicker than Mars’). It even has oceans and rivers, clouds and rain! Except it isn’t a water cycle that creates these, but a hydrocarbon cycle! This is because it is so far from the sun, so the frigid temperatures of -179°C mean that methane and ethane (gases here on Earth) are in a liquid state, and all water above the surface is very much frozen. Beneath the surface, however Titan is one of the many moons believed to have a subsurface liquid water ocean. This makes it a prime candidate in the search for life, both Earth-like/water-based (beneath the surface), and more unexpected forms. The dragonfly mission, launching in 2026, might get closer to answering this question as one of its many aims. 

The other gas giants also have weather systems- Uranus and Neptune are ice giants, so their atmosphere’s are quite hazy, making weather systems difficult to distinguish. But upon further investigation (eg. by using infrared telescopes), it was discovered that Neptune has a ‘Great Dark Spot’: an anticyclone similar to the famous one on Jupiter. What makes Uranus peculiar is that it is tilted on its side, so its equator is where the poles should be, and it rotates like a somersault, rather than a spin! When probed in the infrared, it confirmed that its atmospheric bands and jets are also vertical to the plane of the solar system. This makes sense, as movement of major wind patterns on earth are also governed by the rotation of the planet!

Coming back closer to Earth, Venus, often considered our twin planet, has a hellish atmosphere that results in extreme weather. Like Uranus, Venus doesn’t spin in the same direction to its orbit, as it has been knocked over! It spins almost completely upside down, which makes it more difficult for it to spin, making it the slowest spinning planet in the solar system: only 6km/h vs Earth’s 1700km/h at the equator. So a solar day (the time it takes for the sun to return to the highest point in the sky) on Venus is 117 days! This makes for a huge temperature difference, but we’ve already said that temperature difference drives winds, so on Venus, the wind speeds around 300km/h at the top of the atmosphere, redistributing the air across the whole planet. This, along with the fact that it’s tilt is now only 3° from the normal, means that everywhere on its surface is pretty much the same temperature! It also makes it almost analogous to some exoplanets, which are tidally locked to their star.

Venus
Venus is hidden beneath its thick atmosphere

Around 2.5 billion years ago, the sun was no longer in its infancy, and its energy output had increased enough to cause all of Venus’ oceans to evaporate. Water vapour has a strong greenhouse effect, and added to the mainly CO2 atmosphere, led to a runaway greenhouse effect that resulted in Venus being crowned the hottest planet in the solar system- a toasty 465°C! This thick atmosphere creates intense pressure at the surface (over 90x pressure on Earth, which has caused the death of many-a spacecraft), produces clouds capable of lightning storms, and sulphuric acid rain! All this makes Venus incredibly interesting to study, but also acts as a warning to us here on Earth- if we don’t change our fossil fuel use, then our habitable haven could easily turn into a hellhole rivalling Venus!

Dust storms on Mars
Image showing what Mars normally looks like vs when it has a global dust storm via Phys.org

Finally, although The Martian (no hate, it’s one of my favourite books) depicted Mars’s atmosphere as capable of mass destruction, it is actually so thin that even when winds reach their top speed of ~60mph~ *gasp* it has nowhere near enough power to rip apart equipment and push over rockets, as demonstrated in the 2015 film/2011 book. Because Mars’ atmosphere is only 1% as dense as Earth‘s, even a 60mph wind would have little effect! However, although the dust storms aren’t as dangerous as depicted, they pose a great risk to any solar powered rovers, or in the future, solar powered colonies. They are capable of covering the whole planet, and if they cover any solar panels, it could pose disastrous for a mission if it couldn’t then clear the dust! 

Space Images | Seasonal Changes in Mars' North Polar Ice Cap
via JPL, showing the ice cap size seasonal fluctations.

Like Earth, Mars has seasons. Unlike Earth, during the winter, it gets cold enough that the atmosphere freezes onto the poles! This results in atmospheric pressure fluctuating over the year, and the poles growing and shrinking on a larger scale than on earth. 

It’s not just weather *on* planets that scientists spend time researching. Perhaps the type of extra-terrestrial weather most capable of impacting us is Space Weather. This isn’t really weather in the usual sense, as rather than the effect of the sun’s energy on the atmosphere, it’s the effect of the sun’s matter on anything in its way! The sun continually releases a stream of ionised particles from its outermost layer, which hits with the magnetic field generated by the Earth’s core. The ionised particles are funnelled by the magnetic field to the poles, where it interacts with the atmosphere and energises molecules in the atmosphere so much that they give off light: the aurora borealis, a beautiful phenomenon. But space weather can also be dangerous. The solar wind is radiation, and although the magnetosphere and atmosphere protect us from it’s potential harm, it does pose a risk to anyone who ventures out of our protective bubble (i.e. astronauts).

Magnetosphere: Definition & Facts - Video & Lesson Transcript ...
via Study.com

The more violent end of space weather can also be dangerous to us, despite the natural defences: Coronal Mass Ejections are large bursts of plasma (ionised material) being released at once. These themselves are strongly magnetised, so when one hits Earth, it can momentarily disrupt the magnetic field, causing damage to satellites, and long lasting power outages! However it’s fairly unlikely that we will get hit by one any time soon.

Sun Shoots Out 2 Coronal Mass Ejections | NASA
NASA image of the sun’s corona during a CME (at the top left)

 

It’s safe to say that Earth really is the most habitable planet, with moderate wind speed and temperatures making life rather pleasant, even during a pandemic! By measuring the weather and climate on other planets, we gain an insight into how the universe works, how the earth used to be, how earth came to be habitable, and learn to predict what could come in the future… if we don’t want to end up more like our sister planet Venus, we need to combat climate change, and listen to experts. 

And remember- when you can’t trust an atom, trust in science! Stay Curious, Stay Home, Stay Safe! 

P.S if you’re looking for a way to stay curious at home, check out my Instagram, where I shared some of my own ideas, and recommended some others! 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s