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What is Hubble’s law eq?
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ASTR101 Final
| Question | Answer |
|---|---|
| What is Hubble’s law eq? | V = H0d V= velocity H0: 71 km/s/MPC d= distance |
| What is Hubble's law? | Galaxies are receding from each other at speeds proportional to their distance as the universe expands |
| If you had to guess, according to fossil evidence, how far back in time did life on Earth exist? A. About 10,000 years or less. B. About 100 million years. C. About 3 billion years or more. D. About 3 million years. E. About 1 million years. | About 3 billion years or more |
| What causes the high temperature on the surface of Venus? | Runaway greenhouse gas effect with a thick atmosphere |
| Compared with our Sun, most stars in the Milky Way’s halo are: | Old, red, and dim and have fewer heavy elements |
| What makes up the interstellar medium? | Mainly made up of gas and dust; needed for star formation to occur |
| How long does a galaxy collision typically take? | Hundreds of millions of years |
| The distribution of galaxies in space is | how galaxies, stars, and other celestial objects are arranged throughout the universe. Their positions are measured through redshift. |
| One way astronomers deduce that the Milky Way has a disk is that they | see far more stars along the band of the Milky Way than in other directions? |
| How does a supernova explosion occurs happen? Hint: Think about life cycles of stars. | a massive star reaches the end of their life so its core has gravitational collapse |
| When two galaxies collide with each other as far as disruption? A. very hot gases are formed. B. sucked into black holes. C. collision of their stars D. the gravit- tidal forces that one exerts on the other. E. the big explosions from a collision. | The gravitational (tidal) forces that one exerts on the other |
| Write out the distances of the following in (AU or Light Years). Of these, which of the following is the *farthest* from the Sun? A. Oort Cloud B. Jupiter C. Neptune D. Earth E. Asteroid Belt | Oort Cloud: Between 2000-5000 AU (farthest from the Sun) Jupiter: 5.2 AU Neptune: 30 AU Earth: 1 AU Asteroid Belt: Between 2.2-3.2 AU |
| Solar System Formation: The numerous craters that we see on solid surfaces of most bodies in the solar system are evidence that | The solar system experienced a period of heavy bombardment by leftover debris early in its history |
| Where are most heavy elements made? How? | During supernova explosions (creating iron), this process is called supernovae nucleosynthesis. Or when neutron stars collide, so rapid neutron capture process creates elements heavier than iron like gold and platinum. |
| Which of these best describes what we think dark matter is? | Mass deduced to be present from its gravitational effect but which emits no visible light or other detectable radiation. |
| You observe a distant galaxy. You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared. What do you conclude? | The galaxy is moving away from you. |
| Betelgeuse is a star that is intrinsically much more luminous than the Sun, yet has a surface temperature only about half that of the Sun. Betelgeuse must be a what type of star? | Red Supergiant (large radius and lower temp) |
| The observed position of the Sun relative to the background stars changes each day because of | The actual motion of the Sun through space |
| What are some reasons that the Moon has no atmosphere? | 1. Low gravity due to small size (atmosphere would get quickly lost into space) 2. Lack of magnetic field (atmosphere would get stripped with solar wind) |
| Write out each of the following and then put these in order from smallest to largest. A. The diameter of the Sun B. 1 light-year. C. The size of Pluto’s orbit. D. The size of a typical galaxy. E. Distance to the nearest star (other than our Sun) | Order from smallest to largest: A. The diameter of the Sun C. The size of Pluto’s orbit B. 1 light-year E. Distance to the nearest star (other than our Sun) D. The size of a typical galaxy |
| The pulses seen from a pulsar are caused by | The star’s rapid rotation sweeping beams of radiation across the viewer’s line of sight |
| Based on Kepler’s third law, you can be sure that the orbital period of a planet very near the Sun like Mercury must be | Very much shorter than the orbital period of the Earth |
| Write out the frequency and wavelength of the following. Put them in order of increasing energy A. Infrared. B. Red visible light. C. Violet visible light. D. Radio waves. E. X-rays. | D. Radio waves A. Infrared B. Red visible light C. Violet visible light E. X-rays |
| A star which is very luminous but cool must | Have a very large diameter. |
| Which of the following is a statement of the *fact* of evolution? | Forms of life change over time, via descent with modification. |
| Of these, which makes the most sense as to why space isn’t expanding within systems such as our Solar System? | Gravity is strong enough to hold us together against expansion. |
| At what phase of the moon do we get a solar eclipse? | New moon phase |
| What is our beset guess, based on current estimates, for roughly how old the universe is? | 13.8 billion years old Through measurements of cosmic microwave background radiation and the expansion of the universe through Hubble's law |
| What is the most accurate way to determine the distance to a *nearby* star? | Stellar parallax. |
| What is the Local Group? What are some properties about it (i.e. number of stars, number galaxies, etc.) | An collection of galaxies, in total, there are 50 galaxies in total. 3 big spirals are the milky way, andromeda (largest), Triangulum (smallest of the 3). There are few irregular galaxies and several dwarf galaxies. The distance is 1-2 mil light years |
| In orbiting around the Sun, a planet A. is moving faster when it is closer to the Sun B. always moves in a circle C. always moves in a straight line D. moves slower when it is closer to the Sun E. is never accelerating | is moving faster when it is closer to the Sun |
| Which of the following methods would one use to determine the distance to a nearby galaxy such as the Andromeda galaxy? | Cepheid variables |
| What is Gravity? What type of force is Gravity? | Gravity is a pulling force that works between any two objects with mass. It’s a non-contact force, which means it can work over a distance, even though the objects don't touch each other |
| Which of the following is a consequence of Hubble’s Law? | The more distant a galaxy is from us, the faster it appears to move away |
| How is a neutron star is thought to be created? | A massive star runs out of fuel causing gravitational collapse. Electrons and protons combine quickly to form neutron. It leaves an extremely dense core full of neutrons, creating a neutron star. The outer layers are blown away by a supernova. |
| Why are spiral arms bright? | Spiral arms are the region where most young stars are born, making the arms glow from being bright and hot. There's also a lot of gas and dust which the material scatters reflects and scatters light making it bright. |
| How do we get the seasons of the Earth? | It's caused by the Earth's axial tilt. This tilt means different parts of the Earth get more or less sunlight at different times of the year. |
| If you move towards a light source rapidly, it will look A. redder. B. dimmer. C. cooler. D. unchanged. E. bluer. | bluer |
| Of these, which is likely FALSE? A. A closed universe expands to a max size and then contracts. B. An open universe expands forever. C. A closed universe has a definite start. D. An open universe has no start. E. An open universe could be superlarge. | An open universe has no beginning. |
| How is our sun going to end? What would you expect the Sun will become eventually? | Our Sun will eventually run out of fuel and expand into a red giant. After that, it will shed its outer layers, creating a planetary nebula, and its core will shrink into a cool, dim white dwarf |
| Which planet has a surface very much like that of our Moon? A. Mercury. B. Jupiter. C. Mars. D. Io. E. Venus. | Mercury |
| What is meant by the cosmic background radiation? | It is radiation created during the early days of the Universe. |
| Consider the force of gravity between two masses M1 and M2 separated a distance D apart. If we HALVED the distance between the two masses, how does the force of gravity between them change? (Hint: use the universal law of Gravitation) | F= G(M1)(M2)/D^2 F=G(M1)(M2)/(D/2)^2 4 x G(M1)(M2)/D^2 The force of gravity increases by a factor of 4 |
| If the Moon were twice its present distance from Earth | Tides would become smaller than they are now |
| Name one different observations (which could be astronomical or on Earth) that suggested to the ancients that the Earth is not moving. prt 1 | 1. The apparent motion of the sun and stars: The Earth isn't moving are constellations show up in the same time each year along with the sun rising and setting in the same direction everyday |
| Discuss how these were later understood in terms of the Sun-centered model of the solar system prt 1 | 1. Heliocentric model shows apparent motion of the stars is due to Earth's rotation but the stars themselves are not actually revolving around Earth. The vast distance to the stars also means that their motion is not perceptible in short periods of time |
| Name one different observations (which could be astronomical or on Earth) that suggested to the ancients that the Earth is not moving. prt 2 | 2. No observable parallax with stars: When people looked at stars from different points of earth, the position of nearby stars to Earth wouldn't shift their position |
| Discuss how these were later understood in terms of the Sun-centered model of the solar system prt 2 | 2. The heliocentric model explained that the Earth's motion around the Sun does cause parallax, but the distances involved were so vast that the effect was not detectable with ancient tools until telescopes were created |
| Describe the evolution of the Sun, from its formation to its final stage as a compact object. | 1. Formation: The Sun formed from a cloud of gas and dust that collapsed under its own gravity, triggering nuclear fusion at its core. This marked the start of the Sun’s life as a main-sequence star. |
| Describe the evolution of the Sun, from its formation to its final stage as a compact object. | 2. Main sequence: It spends most of its life fusing hydrogen into helium in its core, producing energy and light as an main sequence star. |
| Describe the evolution of the Sun, from its formation to its final stage as a compact object. | 3. Red giant: As the Sun runs out of hydrogen in its core, it will start to fuse helium and other heavier elements, causing it to expand become a red giant. |
| Describe the evolution of the Sun, from its formation to its final stage as a compact object. | 4. Planetary Nebula: After shedding its outer layers, the Sun will expel a large part of its mass, forming a glowing cloud of gas known as a planetary nebula, leaving behind a dense core. |
| Describe the evolution of the Sun, from its formation to its final stage as a compact object. | 5. White dwarf: The remaining core will cool and shrink into a white dwarf, a small, dense, and faint remnant of the Sun |
| You observe two stars of identical luminosities. Star 1 is at a distance of 10 million light years and we measure its brightness to be 1 unit. We measure the brightness from star 2 to be 1/81 units. Derive the distance to star 2. | Star1/Star2 = (d2/d1)^2 1/(1/81) = (d2/10)^2 81 = (d2/10)^2 sq rt 81 = d2/10 9 = d2/10 d2 = 90 million light years Star 2 is 90 million light years distance |
| In class we discussed three major parts of the Milky Way galaxy. Draw a diagram of the Milky Way, with arrows clearly labeling and naming each of the three parts. Also indicate where most of the hot young stars are currently forming | The Disk: This is the flat, spiral region of the Milky Way where most of the stars are located. The spiral arms of the disk are where most of the hot young stars form, where new stars form from the gas and dust. |
| In class we discussed three major parts of the Milky Way galaxy. Draw a diagram of the Milky Way, with arrows clearly labeling and naming each of the three parts. Also indicate where most of the hot young stars are currently forming | The Bulge: Located at the center of the galaxy, the bulge has older stars The Halo: Surrounding the disk and the bulge, the halo is a roughly spherical region containing sparse stars and globular clusters Look at phone for diagram |
| Name the three major types of galaxies. Contrast the three in terms of shape and the types of stars found in the galaxies | Spiral Galaxies: Shape: Flat, with a central bulge and long, winding arms (like the Milky Way). Stars: Contain both old and young stars, especially in the spiral arms, where new stars form. |
| Name the three major types of galaxies. Contrast the three in terms of shape and the types of stars found in the galaxies | Elliptical Galaxies: Shape: Oval or round, with no distinct arms or disk structure. Stars: Mostly older stars, with little to no new star formation. |
| Name the three major types of galaxies. Contrast the three in terms of shape and the types of stars found in the galaxies | Irregular Galaxies: Shape: No defined shape, often irregular or asymmetric. Stars: Contain a mix of old and young stars, with active star formation in some area |
| Why should we expect that collisions between galaxies are fairly common, but collisions between stars are not | Galaxies are big and have strong gravitational interactions, so they can collide. Stars are far apart, so even in a galaxy collision, stars usually don’t collide directly. Instead, their gravitational fields might cause stars to move or change orbits. |
| List and discuss *briefly* the three distinct pieces of evidence we covered in class that support the idea of the Big Bang. Be specific! a. First piece of evidence | 1. (CMB) Radiation is a faint glow of radiation left over from the early universe, detected in all directions. It matches predictions for the heat leftover from the Big Bang, showing the universe was once extremely hot and dense |
| b. Second piece of evidence | 2. Redshift of galaxies meaning, light from distant galaxies is moving away from us. The redshift shows that the universe is expanding, consistent with the idea that the universe began from a single point and has been growing ever since |
| c. Third piece of evidence | Abundance of light elements: Which is hydrogen and helium. The Big Bang theory predicts these exact ratios of elements, which matches what we observe in the universe today |
| What is the concept of inflation in the universe? | Inflation is the early universe went through rapid expansion, faster than the speed of light during a tiny fraction of a second. |
| Discuss *briefly* one problem solved by the idea of inflation | It solves the horizon problem by all regions were once very close together before expanding rapidly. This allowed them to be in contact and share the same temperature, explaining the uniformity we see in the universe today |
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