Question 1

If scientists discovered for a fact that dark matter and energy is real would we have a hypothesis on how it would affect our universe? If so how would it?

Accepted Answer

We actually have observed both dark matter and dark energy! We first discovered dark matter from its gravitational effects on galaxies. People calculated that galaxies were spinning so fast that the gravity from their visible matter wasn’t enough to keep them from flying apart. That means there must be some mass that isn’t just regular matter: dark matter.

Since (as far as we can tell) dark matter only interacts with the rest of the universe via gravity, that’s what we have to use to study it. Another gravitational effect is gravitational lensing. This happens when light bends when it travels around massive objects. General relativity predicts gravitational lensing, and we first confirmed it by measuring where stars around the sun appeared during solar eclipses. Their light does appear to come from different directions when the sun is near them. For dark matter, we also observe that the light coming around it appears distorted as well.

Dark energy makes the expansion of the universe speed up. We’ve observed the light from distant stars and discovered that the further a star is from us, the faster it appears to be moving away from us. This happens because space itself is expanding. We know the universe is expanding, but for a while we didn’t know if its expansion was getting slower or faster with time, or if it was just expanding at pretty much the same rate.

Gravity makes things with mass pull together. Specifically, it makes massive things that are moving apart (like they are in our expanding universe) start to move apart more slowly and eventually start moving together. People thought, then, that gravity might be slowing its expansion down. So, they set out to observe more distant stars again to test this prediction.

The universe’s expansion wasn’t slowing like they thought, though! It was speeding up. We call the thing that counteracts gravity (over very long distances) and makes the universe expand faster and faster dark energy.

Does that answer your questions at all? There’s still a lot we don’t know about dark matter and energy, so people are studying them!

Question 2

why didn't the sun cool down

Accepted Answer

Stars don't usually cool down. They usually get hotter and hotter over a long period of time. So instead of the sun cooling down it will most likely end up heating up.

Question 3

do you believe that there are other sources of life on different planets in our solar system

Accepted Answer

The only evidence that we have of potential life elsewhere in the solar system comes from Martian meteorite "Allan Hills 84001". It's a rock from Mars that appears to contain fossilized bacteria. Most scientists reject the hypothesis that the structures in the meteorite are fossils and instead believe that they were produced abiotically. But, it is still debated and at this point we don't know for sure.

Question 4

What was the first other planet found other than Earth, it seems that there are so many out there and it's just crazy!

Accepted Answer

The first planets to be discovered were Mercury, Venus, Mars, Jupiter, and Saturn. They were discovered more or less at the same time because they all can be seen with the naked eye. Uranus and Neptune weren't discovered until after the invention of the telescope.

Question 5

How does the same water dinosaurs drank and other animals from the past drank not diteriate over time considering the waters been on the earth for trillions of years.

Accepted Answer

When water evaporates, it goes back into the atmosphere and forms clouds, it later falls back down as rain. The water cycle keeps water moving, but never gone.

Course: Middle school Earth and space science - NGSS > Unit 1

Introduction to Middle school Earth and space science

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