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

What are the components of the solar system?

Solution: The Sun, planets, moons, rings, asteroids, comets, and dust.

Question 2 Show/hide solution

Where in the solar system have human beings landed so far?

Solution: Only on the Moon.

Question 3 Show/hide solution

What do all the planets' orbits have in common?

Solution: They orbit in roughly the same plane.

Question 4 Show/hide solution

Which are the terrestrial planets?

Solution: Mercury, Venus, Earth, and Mars.

Question 5 Show/hide solution

What is an AU (astronomical unit)?

Solution: The distance from Earth to the Sun, equal to around 150 million km.

Question 6 Show/hide solution

How big is Saturn?

Solution: Around 120,536 km in diameter.

Question 7 Show/hide solution

What is the least dense planet in the solar system?

Solution: Saturn.

Question 8 Show/hide solution

What is the least massive planet in the solar system?

Solution: Mercury.

Question 9 Show/hide solution

Which planet's distance from the Sun is about half the distance of Saturn?

Solution: Jupiter.

Question 10 Show/hide solution

How do asteroids differ in composition from comets?

Solution: Asteroids are made of rock, while comets are made mostly of ice.

Question 11 Show/hide solution

What is the difference between a meteor and a meteorite?

Solution: A meteor is a flash of light caused by a particle that enters Earth's atmosphere and burns up. If the particle doesn't completely evaporate, it eventually hits the ground, and it is then called a meteorite.

Question 12 Show/hide solution

What is differentiation, in the context of planets?

Solution: The natural separation of the planet's materials into layers of different densities due to the force of gravity.

Question 13 Show/hide solution

Is it possible to build a house on Jupiter?

Solution: No, since it has no surface. Although I guess you could build a floating house.

Question 14 Show/hide solution

What can we find by counting impact craters on a celestial object, and what is the disadvantage of this technique?

Solution: Since the rate of impacts is roughly constant, the number of impacts on the surface can allow us to roughly estimate the age of that surface. However, surfaces often undergo geological changes that erase the craters, so this can only tell us about the age of the surface itself, not the actual age of the object on which the surface is located.

Question 15 Show/hide solution

What can we predict about the emission of radiation from atomic nuclei? What can't we predict?

Solution: We can predict approximately how many emissions will occur in a specific time period, but we can't predict the exact time where the next emission will occur - it's completely random.

Question 16 Show/hide solution

I have 1 kg of radioactive atoms with a half-life of 2 years. How much of these atoms do I have left after 8 years?

Solution: The number of atoms is reduced by half every 2 years, so after 8 years it will be reduced by half 4 times, for a total factor of 1/2⁴ = 1/16. Therefore the final mass will be 1/16 kg. If you're not sure how I did the calculation, simply do it in steps, dividing by 2 for every 2 years that passed. 2 years: 1/2 kg, 4 years: 1/4 kg, 6 years: 1/8 kg, 8 years: 1/16 kg.

Question 17 Show/hide solution

I have a 4 kg sample. 1 kg of the atoms are radioactive, with a half-life of 20 years. The other 3 kg are decay products of these radioactive atoms. How long ago was the sample created?

Solution: Since the sample was created, the number of atoms reduced by half every 20 years. Right now, only 1/4 of the atoms from the original sample remain. Therefore, their quantity was reduced by 1/4. Since 1/2 × 1/2 = 1/4, this means the quantity was reduced by 1/2 (after 20 years) and then by another 1/2 (after another 20 years). Therefore the sample is 40 years old.

Question 18 Show/hide solution

Which decay product of Potassium-40 is used for radioactive dating of rocks?

Solution: Argon-40.

Question 19 Show/hide solution

Could I use Uranium-238 to date a sample that I know to be less than 1000 years old?

Solution: No, since the half-life of Uranium-238 is 4.47 billion years. There hasn't been nearly enough time for any of the atoms to decay yet!

Question 20 Show/hide solution

What is a solar nebula?

Solution: A spinning disk of gas and dust from which a planetary system will eventually form.

Question 21 Show/hide solution

What are planetesimals?

Solution: Small objects that form out of coalesced matter and will eventually gather together to make up a full planet.

Question 22 Show/hide solution

Which planet's surface was mapped by the Magellan mission?

Solution: Venus.

Question 23 Show/hide solution

When was the first landing of a human-made probe in the outer solar system?

Solution: 2005, when the Huygens probe landed on Saturn's moon, Titan.

Question 24 Show/hide solution

Which two planets in the solar system are the least explored, and why?

Solution: Uranus and Neptune, since they are the farthest from Earth, and therefore the hardest to get to. Both have only been explored by the Voyager 2 spacecraft.

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