Please solve the following questions. This is not an assignment, it will not be graded, and you do not need to submit your solutions to anyone. The questions are simply intended to help you practice for the exam.

These questions will not appear in the exam itself. Students who don't genuinely attempt to solve the questions on their own, and only memorize the solutions, will have a very hard time in the actual exam!

These questions are not multiple-choice, to encourage you to think of the answers on your own, but the questions in the actual exam will be multiple-choice.

If you need any clarifications for these questions, you can ask for them on the course Teams channel.

Question 1 Show/hide solution

"It is known that the model of the universe that we have right now is 100% correct." True or false?

Solution: False. There are still things our model does not explain (for example, dark matter), but more importantly, in science, nothing is ever considered the absolute and final truth, and we are always ready to replace any model if a better one provides a better match to experimental data.

Question 2 Show/hide solution

What is a scientific model called before it is verified experimentally?

Solution: A hypothesis.

Question 3 Show/hide solution

What happens if the results of experiments disagree with the predictions of a scientific theory?

Solution: The theory is no longer considered correct, and we need to find a better one.

Question 4 Show/hide solution

What is a challenge that astronomy has, which other sciences generally don't have?

Solution: In astronomy, since we are studying objects that are extremely far away, we cannot do experiments in a lab. We can only observe these objects from afar using telescopes.

Question 5 Show/hide solution

A famous astronomer wrote a paper with a new theory. The theory has not been tested experimentally, but the astronomer is VERY famous. Can we assume that the theory is correct?

Solution: No. While the astronomer may call this idea colloquially a "theory", it is still just a hypothesis, and must be confirmed in multiple experiments before it is considered correct (and even then, it could still be replaced with a better one later). It doesn't matter how famous you are, you are never exempt from this rigorous scientific process.

Question 6 Show/hide solution

What was the new class of astronomical objects predicted by Einstein's theory of relativity?

Solution: Black holes. We will learn more about them later!

Question 7 Show/hide solution

Is the number 3×10⁷ smaller or larger than the number 6×10⁵?

Solution: Larger. The first number is 30,000,000 and the second number is 600,000, which is clearly smaller. In general, the number with the larger exponent will always be the larger number.

Question 8 Show/hide solution

What is a light-year?

Solution: It's the distance light travels in a year, or approximately 9.5×10¹² kilometers.

Question 9 Show/hide solution

"A fast race car can reach speeds of up to 10% of the speed of light." True or False?

Solution: False. The speed of light is 300,000 kilometers per second. 10% of that is 30,000 kilometers per second. Have you ever seen a car that can travel 30,000 kilometers (around 9 times the distance from Toronto to Vancouver) in 1 second?

Question 10 Show/hide solution

Which is longer, a meter or a kilometer?

Solution: A kilometer. A kilometer is equal to 1,000 meters.

Question 11 Show/hide solution

I observed a supernova (an exploding star) in the sky this year. The distance to the supernova was 12,000 light-years. How long ago did the star actually explode?

Solution: 12,000 years.

Question 12 Show/hide solution

What does the Earth have that no other planet in the solar system has?

Solution: As far as we can tell, it is the only planet in the solar system where sentient life has evolved.

Question 13 Show/hide solution

How many planets are in the solar system? Can you name all of them?

Solution: There are 8 planets. From closest to farthest from the Sun, these are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. To remember them, you can use the mnemonic: "Many Very Educated Men Just Screwed Up Nature."

Question 14 Show/hide solution

Which planet is the closest to the Sun? Which planet is the farthest away from the Sun?

Solution: Mercury is the closest, Neptune is the farthest.

Question 15 Show/hide solution

What's the difference between a planet and a star?

Solution: A star produces its own light, a planet doesn't.

Question 16 Show/hide solution

What is the closest star to the Sun? How far is it? How long does it take light from that star to get to us?

Solution: Proxima Centauri is the closest star, at 4.2 light-years away, which means light takes 4.2 years to get to us from that star.

Question 17 Show/hide solution

"There are several million stars in the Milky Way Galaxy." True or false?

Solution: False, there are hundreds of billions of stars in the galaxy.

Question 18 Show/hide solution

Is the Sun at the center of the Milky Way Galaxy?

Solution: No, it is not. We are not the center of the universe! Our Sun is around 30,000 light-years away from the center of the Galaxy.

Question 19 Show/hide solution

Have astronomers been able to take photos of the Milky Way Galaxy from outside the galaxy?

Solution: No, this is impossible, as it would require sending a spaceship thousands of light-years away from the galaxy. Even if we had the technology to do that, it would take thousands of years before we can receive the photos. We are only able to take photos of the Milky Way from the inside, since we are inside it.

Question 20 Show/hide solution

Is Andromeda the nearest galaxy to us?

Solution: No, it is the nearest LARGE galaxy to us. There are smaller galaxies that are closer to us. (The nearest galaxy is called the Sagittarius Dwarf Galaxy.)

Question 21 Show/hide solution

What is the name of the cluster of galaxies that the Milky Way belongs to?

Solution: The Local Group.

Question 22 Show/hide solution

What is the name of the supercluster that this cluster belongs to?

Solution: The Virgo Supercluster.

Question 23 Show/hide solution

"Oxygen is the most abundant chemical element in the universe." True or False?

Solution: False. Hydrogen is the most abundant chemical element. This is because it's the lightest simplest element, with just 1 proton in each atom.

Question 24 Show/hide solution

What are the 3 types of subatomic particles that atoms are made of?

Solution: Protons and neutrons make up the nucleus, and electrons orbit around it. But the protons and neutrons are made of up and down quarks, so the more precise answer is "electrons, up quarks, and down quarks".

Question 25 Show/hide solution

"Humans have existed for most of the lifetime of the Universe." True or False?

Solution: False. The universe is 13.8 billion years old; humans have only existed for a few hundred thousand years.

Question 26 Show/hide solution

"The Earth has existed since the beginning of the Universe." True or False?

Solution: False. In the beginning of the universe there were no planets, stars, or galaxies. (The universe is 13.8 billion years old; Earth is only around 4.5 billion years old. That's much older than humans, but not nearly as old as the universe itself.)

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