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Astro 7N Exam 1 Questions and Correct
Answers Updated 2025-2026 Graded A
A moon orbits is exactly the same plane as the planet orbits its star. How often does this planet experience a solar eclipse? - ANSonce every orbit of its moon (its month) a new planet orbits its star faster than the earth orbits the sun and it rotates more slowly than he earth rotates. which is true - ANSthe new planet has a shorter year than earth and a longer day than earth A photon's___can be measured to determine its energy - ANSwavelengths or frequency A star(sun) has a surface area temperature of 50,000 kelvin, in which region of electromagnetic spectrum does its peak brightness occur? - ANSUltraviolet According to Newton's Second law of motion, if the net force acting on the object increases while the mass of the object remains constant, what happens to acceleration - ANSacceleration increases And, on the opposite site of the orbit, when the northern hemisphere is tilted the farther away from the sun, the average daily temperature is
marked as____, suggesting that the norther hemisphere is experiencing___ - ANScool;winter approximately two weeks after a solar eclipse, what phase will the moon be in? - ANSfull moon it takes about a month to get a new moon - so a full moon is the half mark (2 weeks) Asteriods - ANS• remnants of the Solar System's formation — rocks left over when the planets form • many are in the "Asteroid Belt" between Mars and Jupiter
- asteroid orbits are typically slightly elliptical
- a few major types exist: carbon-rich, metallic, and silicate (stony)
- we see asteroids by reflected sunlight; they do not shine visibly on their own • the orbits of some asteroids intersect Earth's orbit, and lead to meteors • most are less than 1 kilometer in size, but some are bigger
- like comets, asteroids tend to move very slowly across the sky to a viewer on Earth
Both the mood and the sun rise for the same reason, it is b/c of: - ANSthe rotation of the earth Comets - ANSA few kilometers in size • Made of ice (both water ice and "dry ice") and dust — remnants of Solar System formation • Tails pointing away from the Sun develop due to the solar wind • Shine by reflected sunlight — i.e., comets do not produce light of their own
- Highly-elliptical orbits that take them far from the Sun; as would be predicted by Kepler's 2nd Law, comets spend most of their time in the outer reaches of the Solar System — they zip by the inner Solar System and travel back out very quickly • Comets move slowly across the sky from our perspective on Earth • Short-period comets have periods < 200 years
- long-period comets have much longer periods (can be 1,000s of years) and come from the Oort cloud, as much as 50,000 AU from Sun
- Halley's Comet is a famous short-period comet that returns every 76 years — its last visit to the inner Solar System was in 1986; the next return will be in 206
Compare frequency of x-ray versus regular light - ANSThe X-ray has a larger frequency than visible light. Compare the frequency and wavelength of a gamma ray with visible light: - ANSgamma ray frequency is higher and its wavelength is lower Compared to blue light, red light has - ANSlonger wavelength, smaller frequency, smaller energy Constellations - ANSconstellation = large defined areas of the sky (like states in a map of a country)
- anything visibly within that region is considered "in" that constellation
- there are 88 of them, in all (dividing up the total celestial sphere)
- Stars in the same constellation are likely to be at very different distances from us. Not necessarily close to each other, though they appear close projected on our sky.
- Different constellations are visible at different times of year; e.g., "Orion the Hunter" is prominent in the Winter — because as the Earth travels around the Sun, its nighttime side faces different regions of space.
- ecliptic = the apparent path of the Sun over the course of a year, with respect to the distant stars — also refers to the plane in which the Earth orbits the Sun.
aurora caused by solar wind particles that hit atmospheric gas and lead to emission of different colors; they are prominent near the north and south poles plate tectonics = rocky plates on the surface of Earth float on denser but more-fluid rocky material, and move around — leads to continental drift, mountains caused by collisions of plates; plates sliding past each other cause faults, quakes ozone (three oxygen atoms bonded together) layer (in stratosphere at 6 - 30 miles above the surface) protects Earth from solar Earth pt 2 - ANS"Greenhouse Effect": Energy from Sun heats Earth. Earth's surface radiates this heat back towards space by giving off infrared radiation. •
- Particular gases (including water vapor and CO2) in the Earth's atmosphere recapture and redirect this heat back towards the surface, preventing it from escaping to space.
- This trapped heat is redistributed back on Earth. The naturally abundant greenhouse gases in the Earth's atmosphere act like a thermal blanket keeping Earth warm.
- Without greenhouse gases Earth's surface would be about 33 degrees Centigrade cooler. When humans produce large amounts of greenhouse
gases, it leads to extra heating, potential extra reinforcing feedback loops — i.e., global warming — beyond stabilized longer-term temperatures. Earth's moon (luna) - ANSterra (Latin for "land"): light-colored features, heavily-cratered, high peaks; geologically older; highlands uplifted from impacts in early solar system maria (Latin for "seas"): dark-colored, less cratered, valleys; geologically younger; filled by lava 1 to 4 billion years ago regolith = powdery dust and rocky debris that covers the Moon; broken apart by small meteorites hitting moon continuously impact craters = gouged out from explosions, asteroids or comets that hit the moon The Moon rotates on its own axis with exactly the same period that it takes to travel once around the Earth; consequentially, the same side of the Moon always faces Earth — this is known as "tidal locking" Moon lacks as much high-density material such as iron — no large iron core 1/4 diameter of Earth Moon has no atmosphere; daytime sky is dark
Electromagnetic Radiation / Light pt 2 - ANSA prism splits light into different colors by bending different wavelengths by different angles. The Sun's surface temperature is about 5800 degrees Kelvin. Its spectrum peaks in the visible light region (peak around green — a "green star"!). Room temperature is about 300 degrees Kelvin; a "blackbody" at room temperature peaks in the infrared (IR) region of light. Q: What kinds of radiation get through the Earth's atmosphere? A: visible and radio (so, to be able to see other kinds of light with a telescope — e.g., infrared, x-ray — you would need to place that telescope in space) Formation of the Solar System - ANS1. the Solar System formed 4.5 billion years ago
- starting with cloud of gas and dust, it collapses due to its own gravity
- as it collapses, the spinning cloud flattens and forms a disk
- the Sun forms at center
- "lumps" in the disk become planets
- the regions around these proto-planetary clumps clear out (or material is absorbed)
- only rocks and metals survive in inner region; outside, ices and gases also survive
- takes a few tens of millions of years to form from earth, in which constellation might you find the planet Saturn - ANSTarus How much of the total surface area of the Moon is illuminated by Sunlight during the Full Moon phase? - ANSone half if earth had its orbit changed so that all points along its orbit it were always the same distance from the sun (circular orbit), how would this affect the seasons on earth? - ANSthey would be the same as they are now if earth rotated on it axis more slowly than it does now; - ANSdays would be longer If Earth's Moon was Full on May 1,2007. When was it next in the First Quarter phase after this Full Moon? - ANSMay 22 If I apply exactly the same amount of force to a pebble and a boulder, what will happen - ANSthe pebble will move faster
Jupiter has a small ring system. Jupiter is made mostly of hydrogen and helium gas.
- Gaseous molecules of ammonia, methane, and water vapor also present; these lead to different colors in Jupiter's stripey, swirling appearance.
- Clouds of different colors are also at different altitudes. Windspeeds can reach 360 km/hr; the "Great Red Spot" is a giant storm larger than Earth — like an anticyclone on Earth — and has lasted for at least 300 years Jupiter rotates rapidly (once every 10 hours), which stretches the clouds into long bands. It takes Jupiter 12 Earth years to orbit the Sun. Interior temperatures and pressures get very high, deep inside Jupiter's gaseous body
- Hydrogen gets compressed into a liquid-metallic form.
- In its very center, Jupiter is likely to have a rocky/metallic core. Magnetic fields are 10 times stronger than Earth's due to the rotating liquid- metallic region; interaction between this magnetic field, the solar wind, and Jupiter's atmosphere leads to aurora like we see on Earth
Methane can convert to carbon soot, and high pressures inside Jupiter can compress that into diamonds (leading to "diamond rain" in Jupiter's atmosphere). Life forms in Jupiter's atmosphere were proposed to exist by astronomers Carl Sagan and Edwin Salpeter; these speculative creatures were referred to as "sinkers," "floaters," and "hunters." Jupiter pt 2 - ANSJupiter has more than 50 moons;
- the four largest were discovered by Galileo in the early 17th century CE; they looked like stars, but were found to orbit Jupiter — important because it helped demonstrate that Earth is not the center of Universe
- Using Kepler's laws, the mass of Jupiter can be measured using the periods and semimajor axes of the orbits of Jupiter's moons; periods range from 1.8 to 17 Earth days, and Jupiter's mass is about 317 Earth masses.
- You should remember the names and basic information (below) for these four largest "Galilean" moons of Jupiter Jupiter's moon Callisto - ANSthe farthest out of the four large Galilean moons; very heavily cratered — many young craters; does not get heated much, and has not changed much since its formation; about the size of the planet Mercury Jupiter's moon Europa - ANSwater-ice surface; no craters — ice movement wiped them out; liquid water ocean below icy crust
a blue photon does not move faster than a red photon b/c they are bot traveling at the speed of light mars - ANSMars' days and nights are similar in length to those on Earth About half Earth's diameter; 1/10th Earth's mass
12 spacecraft have visited Mars; rovers explored surface No thick atmosphere, but does have thin one that causes orangish sky; mostly carbon dioxide; only modest Greenhouse effect because the atmosphere is so thin
- Average surface temperature about -65 ˚C, but can be warmer at its equator • Iron oxide ("rust") in surface rocks gives Mars its red color Has two moons, Phobos and Deimos, but they are tiny — only 0.3 % of Mars' size Olympus Mons (large volcano on Mars; do not need to remember name) is 3 times higher than Earth's highest mountain; Martian volcanos appear dormant •
Valles Marineris (do not need to remember name) is the deepest canyon in Solar System — about 300 times size of the "Grand Canyon" on Earth • Water once existed on the surface of Mars, but it is not flowing regularly there at present; permafrosts = water ice locked beneath Martian soil Dust storms are common; occasionally make it hard to see surface features. Mass - ANSAs the mass of the planet increases, the jump height does decreases by the same factor As the mass of the planet decreases, the jump height does increases by the same factor Mercury - ANSgreyish w/ numerous craters looks a like Earth's moon, but does not have prominent maria, the dark "seas," like the Moon does
- Can only see close to Sun — and hard to do with the naked eye. Displays phases. Mercury is much smaller than Earth. It is similar to Mars in mass and radius, and only a bit bigger than Earth's Moon; surface gravity less than on Earth
- most meteors are tiny dust particles or grains — less than a centimeter in size — that rapidly burn up in Earth's atmosphere; pieces of Solar System debris • meteors occur when an asteroid crosses Earth's orbit, or when Earth passes through a cloud of debris left behind by a comet passing through the inner Solar System (the famous Halley's Comet is reponsible for the "Orionids" annual meteor shower)
- a "fireball" = very bright meteor due to larger-than-usual chunk of debris
- a "meteorite" = piece of meteor that survives atmospheric entry, hits Earth's surface • asteroid collisions were more common in the younger Solar System • 65 million years ago a large meteor collision with Earth contributed to the extinction of dinosaurs (the "K/T event"); dust and smoke thrown into the atmosphere was greater cause of extinction — not so much the initial impact itself moon and earth - ANSthe moon's orbit around earth is actually tipped about 5 degrees to earth's orbit around the sun so the moon isnt always in the right plane for an eclipse to occur Phobos eclipses: every orbit
Mars had a one degree inclination, which is different from Earth's Moon's inclination of 5 degrees. That inclination of Earth's Moon's orbit explain why eclipses are very rare on earth Moon phases - ANSQ: How are the Sun, Earth, and Moon positioned when it is a solar eclipse? A: Sun — Moon — Earth (as in a new Moon). Q: What is a lunar eclipse? A: Earth's shadow passes across the Moon. Q: How are the Sun, Earth, and Moon positioned when it is a lunar eclipse, and what phase is the Moon in? A: Sun — Earth — Moon (as in a full Moon). Q: Why do eclipses not occur every month on Earth? A: The Moon orbits the Earth in a slightly different plane than the Earth orbits the Sun. Q: What about eclipses of the moons of Mars? A: Mars has two small moons, Phobos and Deimos. Relative to Earth's Moon, they are tiny, and closer to their planet and orbiting faster — and closer to the orbital plane of Mars around the Sun. This leads to more frequent eclipses visible from Mars.
