astroEDU 1303: Script of Design Your Alien activity
Today you're going to design your own Alien!
We'll split you up into teams.
You'll each chose 1 of 4 worlds within the Solar System
Then design an alien suited to that environment.
Before you start though, let's get some ideas how life might adapt to different environment.
Let's take Earth as an example first, since it's the only place we know of that actually has life!
So, what makes the Earth “just right” for life?
Q: What does life here need to survive?
Air is the gas of Earth's atmosphere which is held in place by our planet's gravity.
The atmosphere stretches up to space getting thinner as it goes. Although there's no real boundary between our atmosphere and space, we guess it's around 100km. We call this the Kármán line.
But we can only breathe up to about 8000m.
The atmosphere is very important to life on Earth. Space is an airless vacuum so we couldn't breathe there. Thanks to our atmosphere we can breathe on Earth. And not just oxygen! As you know, plants “breathe” carbon dioxide and scientists found a new creature at the bottom of the ocean in 2010 that doesn't need oxygen to survive either. There strange little creatures are called Loricifera and they live in parts of the sea with almost no oxygen. (Scientists are still doing research to find out how they survive.)
The atmosphere also provides protection from harmful cosmic rays. Like Ultraviolet radiation, X-rays and Gamma rays. The Sun sends lots of UV rays at the Earth (these cause Sunburn!) that we know can be dangerous to humans, they damage our eyes and can cause skin cancer. X-rays and Gamma rays come from the really energetic events in the universe, Supermassive black holes and supernova (the explosive deaths of massive stars) These rays are very damaging to living cells, even deadly!Luckily our atmosphere absorbs most of these rays and stops them reaching the surface!
Small Temperature Slide
The atmosphere is important for another reason, regulating the temperature on the Earth's surface.
Our atmosphere acts like a blanket. During the day it protects us from the extreme heat of the Sun. While at night it keeps out the chilling cold of Space ( 234.45 celcius). Space is just a few degree above absolute zero which is the lowest temperature possible!
Big Temperature Slide
For example, the Moon is about the same distance as Earth from the Sun. But the temperature on the Moon is very different from Earth. Although the moon does have an atmosphere, it's not really worth mentioning. It is extremely thin, very unstable and because of the Moon's low gravity it is constantly blowing into space.
Point to Earth-Moon temperature comparison
These are the extreme temperatures on the Moon and Earth, look how different they are!
Q: So what would happen if our atmosphere was thinner?
A: - We might need bigger nostrils to suck in more air at one time?
- We would need to be more adaptable to temperature change, maybe retractable body hair, or the ability to turn your skin into a mirror and reflect heat?
- We'd need thicker skin made of a stronger material to protect us from cosmic radiation.
Q: What would happen if our atmosphere was thicker?
A: - We might need better vision or other ways of “seeing” through the fog.
- It would hold heat much better so, depending on how far the world is from the Sun, it may get quite hot. Maybe it lives underwater (if there is water!)
This brings us to the next important feature of our world: its distance from the Sun.
Distance from the Sun.
A world's distance from the Sun is important because it affects the temperature there, which directly determines the existence of another key factor of life – Water.
Every planetary system has a band we call “The Habitable Zone”. This is the area are just the right distance for liquid water to exist – not too hot, not too cold.
Habitable Zone Slide
This blue band shows the habitable zone in our Solar System, you can see the Earth sits comfortably inside. Mars is also in the habitable zone.
Q. Does this surprise you?
A. We know that liquid water used to exist on the surface of Mars for millions of years. And not just a little, the Mars rover Curiosity has found evidence of deep riverbeds on Mars!
Q. So what might life on a world without liquid water look like?
A. Maybe it would have limbs that can melt ice? Maybe they would be make of rock!
Q. So what else life on Earth need beside air and water?
Food Zone Slide
Plants normally sit at the bottom of the food chain.
Q. What do plants need to survive?
A. Sunshine and Water (which we've talked about)
Skip through three slides as talking about them.
Q. Is there soil on other worlds?
A. Yes! Samples Slide We even have some! The astronauts from Apollo 11 (that landed on the moon) brought back some soil from the Moon! And we know Mars has soil too.
Q. If a world is too far from the Sun and has no solid surface with soil, how will it change the alien life?
A. Maybe they will eat something different, like rocks, and need BIG STRONG SHARP teeth, like steel! Or maybe they will live off gas in the air, and need big nostrils to suck in as much as possible?
Q: Another simple question: What stops us from leaving Earth?
You all know about gravity right? It holds us to the Earth and stops us floating off into Space.
You probably know that gravity isn't as strong on the moon, so people can jump higher and fall slower.
Q. So how would weaker or stronger gravity affect life on another world?
A. - Stronger: Creatures might evolve lower to the ground, like snakes or insects.
- Weaker: There might be more flying animals, like birds! Or they could grown taller and heavier, like elephants.
Let's do an Example. Here is some information about Mars.
Q. Does anyone have any ideas what a creature from Mars would look like based on the environment?
A. Very cold compared to Earth.
Weak atmosphere: no much air.
Weak Gravity: creature lighter, can move easier.
Ice water, but no known liquid water.
Red surface: camouflage?