Understanding Stellar Properties and Cosmic Phenomena in Astronomy

A star that is spectral class A is hotter than a star of spectral class O. Question options: It can take hundreds of billions of years for a red dwarf to convert all of its hydrogen completely to helium. Question options: Red stars are relatively "cold", with low surface temperatures. Question options: A white dwarf is approximately the same size as the Earth. Question options: Fusion only occurs on the surface of the Sun. Question options:

In the conversion from hydrogen to helium, four protons are converted to one helium nucleus. Question options: Occam's razor is the idea that the most simple and most straightforward explanation of observations in nature is most likely to be the correct one. Question options: Sunspots are dark because they are hotter than the surrounding material on the Sun. Question options: All of the terrestrial planets have plate tectonics with converging and spreading plates similar to Earth's. Question options: Red stars are hot and blue stars are cold.

Question options: The Galaxy rotates like a solid disk, like a CD or DVD. Question options: Evidence suggests that planetary formation around stars like the Sun are very uncommon. Question options: Gravitational lensing involves using a special type of lens in a telescope to view gravitational waves. Question options: Two prominent research groups came to the same surprising conclusion after taking measurements of the luminosity of Type Ia supernovae at great distances, this being that the universe is accelerating while it expands. Question options:

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Light has properties of both waves and particles. Question options: What is the solar wind? Question options: waves and vortices on the Sun's surface generated by a solar flare. lux of photons from the Sun's visible surface. n of gases between the equator and the poles of the Sun. er atmosphere streaming out into space. The temperature of the Sun's photosphere is: Question options: K. lion K. Where do we find the most massive stars on the main sequence in a Hertzsprung-Russell diagram? Question options: e approximately the same mass, because this is what defines the main sequence.

ower mass stars on either side The luminosity of a star is: Question options: for its color or surface temperature. as seen by people on Earth. gy output into all space over all wavelengths. at a hypothetical distance of 10 parsecs (32.6 light-years) from Earth. What places a limit on the lifetime of a star? Question options: mass, and therefore of nuclear fuel, of the star into space by stellar winds. of available nuclear fuel it contains. tween stars in a galaxy are sufficiently frequent that all stars will eventually be destroyed in this way. pin as it evolves and contracts means that the star will eventually spin apart. The most likely places in which stars and planetary systems are forming in the universe are: Question options: uter space between galaxies. t gas in the spiral arms of galaxies. nebulae. galaxies. X rays that come from the vicinity of a black hole actually originate from: Question options:

e event horizon. er, or singularity. away from the black hole, where matter is still relatively cool. he event horizon, on the accretion disk. Black holes are so named because Question options: erfect blackbody spectrum. y other electromagnetic radiation can escape from inside them. romagnetic radiation is gravitationally redshifted to the infrared, which leaves no light in the optical region. visible light, their only spectral lines are in the radio and infrared. Spectral lines are of particular importance in astronomy because: Question options: t element has a characteristic line spectrum. bserved through a diffraction grating. nly light bright enough to be seen at large distances. oduce bright line spectra. A significant contribution of Kepler to our understanding of the solar system was: Question options: that Earth orbits the Sun. that planetary orbits are not circular. on of the phases of Venus. gravitational force between Earth and the Sun.

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The age of Earth is considered to be: Question options: llion years. lion years. ion years. ars. Rings of dust and icy particles are found around which planets? Question options: at have moons associated with them. e Jovian planets. e terrestrial planets. What are the most energetic eruptive events to occur on the Sun? Question options: ar explosions minences ejections Compared to a star in the middle of the diagram, a star in the lower left part of the Hertzsprung-Russell diagram is: Question options:

Our Sun will end its life by becoming a: Question options: oud. The central core of the Galaxy is in the direction of: Question options: ula. r. *. How are galaxies spread throughout the universe? Question options: uped into clusters that are spread more-or-less evenly throughout the universe. uped into clusters, which are, in turn, grouped into clusters of clusters (superclusters). densest near the Milky Way Galaxy and become less and less numerous the farther we look out into the universe. spread more-or-less evenly throughout the universe

What is the reason why we have seasons on the Earth? Give as much detail as you can in your own words, but be careful...if you include a misconception, the score is 0. Because of the Earth's tilt of 23.5 degrees as it travels around the sun every year, we have seasons. Every time the North Pole circles the sun, it points to one side. During the year, different parts of the planet receive different amounts of light. In that hemisphere, summer begins when the Earth's axis points towards the sun. Winter is when the Earth's axis points away from the sun. Due to the sun's high position in the sky, its rays hit the Earth at a steep angle during the summer. Since light does not spread out much, each spot receives more energy. It is because of the long daylight hours in the summer that the Earth reaches warmer temperatures. During the summer months, the days are hotter because the Earth has more time to reach warmer temperatures. Due to the lower location of the sun in the sky, the sun's rays hit the Earth at a shallow angle during the winter. As a result, less energy is absorbed in any one spot thanks to the spread out of the sun's rays. Warming of the Earth is prevented by long nights and short days. This question has not been graded. Explain in your own words why we see different phases of the Moon. Identify each of the four major phases, along with a description of what is occurring to allow us to see each of them. Bonus point: At what time is each major phase visible at the Moon's highest point in the sky? Moon phases are determined by its position along its orbit and relative to Earth and Sun. There is no light emitted by the Moon; it simply reflects the sunlight that hits it. Thus, observers on Earth see the Moon with varying degrees of illumination. The four major lunar phases

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New moon This phase reaches its apex at the halfway point in a period when the Moon has rotated around the Earth. In other words, the Moon has rotated 180° around the Earth. In this phase, the Moon is behind the Earth, but its position does not cross the ecliptic which results in an (lunar) eclipse. The entire lunar surface is visibly illuminated, as revealed from Earth. In this phase, the Moon is between the Earth and Sun. However, this is between the appearance of the Moon and the greatest illumination (an eclipse), which occurs in the next phase. This is generally the first lunar phase or the 0° mark. The new Moon is the second of the lunar phases. It is normally invisible to Earth. The old Moon still faces Earth but the far side is more brightly illuminated by the Sun, thus it is more visible than the night side of the Moon. First quarter This phase occurs when the Moon is a quarter of the way through its orbit, beginning with the new moon phase. In other words, since 0°, the Moon has spun 90° around the Earth. As seen from Earth, half of the lunar surface is lighted during the first quarter phase. Full moon This phase occurs when the Moon completes half of its orbit around the Earth. Thus, it is in reverse - it has been flipped 180 degrees as if on its back. This phase causes an eclipse of the moon. The entire lunar surface is visible on the night side. Last quarter This phase comes as the Moon (that is, about half of the sphere) has moved the Earth (that is, about a third of the sphere) into its orbit. At this point, the Moon has turned 270 degrees around the Earth, so we can see half of the Moon's apparent hemisphere. Like the first quarter phase, half of the Moon's surface is visibly illuminated.

The times of each major phase visible at the Moon's highest point in the sky: New moon - noon time (around 12 p.m.) First quarter - sunset (around 6 p.m.) Full moon - midnight (around 12 a.m.) Last quarter - sunrise (around 6 a.m.) This question has not been graded. How does Einstein's famous equation, E = mc2, relate to the production of the Sun's energy? Be sure to include what each factor in the equation represents with respect to what happens inside the Sun. Einstein's famous equation E = mc2 shows that energy (E) and matter (m) are interchangeable. This means that some amount of matter will always convert into energy. The size of the speed of light, and the fact that it is squared, shows that a tiny amount of matter can release very large amounts of energy. E=mc2 says that energy and mass are the same basic stuff, and that mass "m" can be converted to energy "E" and you end up with a huge amount of it. It is what allows stars to use their enormous matter to release unbelievable amounts of energy. As for the sun: Energy = mass × (speed of light)^2. Speed of light c = 300,000 km/s Thousand of tons of hydrogen are converted each second into helium by the sun. There are only a few tons left afterward. Massive amounts of energy were generated from that mass. This is what powers the Sun. A small amount of mass can produce a lot of energy. This question has not been graded. Identify and describe in your own words three separate and specific pieces of scientific evidence that support the Big Bang theory? Cosmic microwave background radiation. Is thought to be the leftover from the big bang explosion.

Galaxies are expanding away from each other. This implies that the universe is expanding because of the observed spectrum that all galaxies are red-shifted. Elements heavier than hydrogen and helium are formed in stars. Where it was discovered that stars are composed of 99% hydrogen and helium in which only these two elements existed after the big bang. This question has not been graded. 78 / 101 - 77.23 % 78 / 101 - 77.23 % Done

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