Astronomy

Featured Answers

Scale and History of the Universe

• Scale of Earth, Sun, Galaxy, and Universe
• Time Scale of the Cosmos
• Light and Fundamental Forces
• The Big Bang
• Expansion of the Universe

Stars, Black Holes, and Galaxies

• Life and Death of Stars
• Quasars and Galactive Collisions
• Stellar Parallax
• Cepheid Variables
• Our Galaxy: The Milky Way

Our Solar System

• The Sun
• The Planets
• Our Moon
• Components of the Solar System
• The Earth

Exploration of Space

• Space Travel History
• Rockets, Satellites, and Spaceships
• Future of Space Travel
• Space Missions

Introduction to Astronomy

• History of Astronomy
• Models of the Solar System
• History of the Telescope
• Astronomy Basics

Uncategorized Questions

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• How fast was comet Shoemaker-Levy 9 going when it hit Jupiter?
• About how fast is an asteroid going when it hits a planet?
• How big is the moon compared to the Earth?
• What causes the phases of the moon?
• What is the difference between prograde rotation and retrograde rotation?
• What planets have no moons?
• What planets do not have eclipses and why?
• What type of star will the Sun become after it leaves the Main Sequence?
• Why do observers in New York State looking due south at the night sky see a different group of constellations from what they had seen six months earlier?
• From which New York State location would Polaris be observed to have an altitude closest to 43° above the northern horizon?
• When is the moon nearest to Earth during its orbit?
• What are Jovian planets also called?
• What are the four Jovian Planets?
• Why didn't the terrestrial planets get as big as the Jovian planets?
• What is the most widely accepted theory of the moon's origin?
• What planetary orbit model allows a scientist to predict the exact positions of the planets in the night sky for many years?
• What does NASA stand for?
• When and where did Giuseppe Piazzi live and work?
• Two stars have the same brightness when viewed from Earth. Is it correct to say the stars are the same distance from Earth and have the same temperature?
• What did Kepler discover about the orbit of Mars?
• Why do stars appear to change position during the night?
• Why is fuel needed to change the speed or direction of a probe in space?
• What does the law of ellipses state?
• How is a comet different from a meteor?
• What are meteoroids?
• What are moon craters? How were they formed?
• Identify the feature that covers much of the moon's surface. What did Galileo see when he observed this feature through a telescope?
• How do temperatures on the moon differ from those on Earth?
• Who was the first person to observe the moon through a telescope? What features of the moon did he identify?
• If an asteroid has a perihelion distance of 2.0 A.U. and an aphelion distance of 6.0 A.U., what is its orbital semi-major axis, eccentricity, and period? Thanks!?
• What is the age of our universe according to astronomers' current estimations?
• What stage does a star remain in for the longest?
• After a supernova, what factor determines whether a star becomes a black hole vs. a neutron star?
• Do living things have to live on the surface of a planet or moon? Where else on a planet or moon could scientists look for evidence of life?
• Why would the discovery of liquid water on another planet be important?
• Why does a comet's tail always stream away from the sun?
• Why do some astronomers think that Pluto should not be called a planet?
• Why does Mercury have only a thin atmosphere?
• What did Copernicus think about the solar system?
• When is the end of the world?
• What conclusion can you draw about a planet's properties just by knowing how far it is from the sun?
• What is so unusual about Uranus's axis of rotation?
• How are the gas giants different from the terrestrial planets?
• Mercury is closest to the sun, yet Venus has a higher surface temperature. Why?
• What are some similarities and differences between Venus and Earth?
• Suppose a certain planet had two moons, one of which was twice as far from the planet as the other. Which moon would complete one revolution of the planet first?
• Why do astronauts on the moon bounce when they walk?
• Does Earth's tilt change as it rotates around the sun?
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• Which planet has the greatest attraction to the sun?
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• How far apart are Jupiter and Saturn? How is this distance calculated?
• What star constellation is recognizable by three stars in the sky, is named after a Greek hunter, and can be found on the celestial equator of the night sky?
• What are the large objects that revolve around the Sun called?
• What is the main difference in the light we see from the planets and the light we see from the stars?
• Why do some of the planets in our solar system appear to be brighter than some stars in the night sky?
• Planets and stars have different positions relative to the Earth. What is the difference?
• What is a neutron star that appears to produce pulses of radio waves called?
• If Copernicus was such a religious man, why did he beheve that a geocentric system was correct?
• If people were so upset by the heliocentric model of the solar system that Copernicus proposed, why did it eventually replace the geocentric version?
• What causes a nova explosion?
• How is nuclear fusion in a main-sequence star different from nuclear fusion in a giant star?
• How is a main-sequence star like the sun able to maintain a stable size?
• What causes the outer shell of a star to expand after it leaves the main sequence?
• If a planet needs 10 years to orbit the Sun, what is the length of its semi-major axis in AU?
• Why do you think the wind speeds on the gas giant planets are so much greater than the wind speeds on Earth?
• How do the periods of rotation and revolution for the gas giant planets differ from those of Earth?
• How does the presence of cosmic background radiation support the big bang theory?
• How does a galaxy that contains a quasar different from an ordinary galaxy?
• The atmospheric composition of which planet is 82.5% #H_2#, 15.2% #He#, and 2.3% #CH_4#?
• If the observable universe is 13.8 billion light years in radius due to the finite speed of light in relation to the total time of the universe's existence, how fast is the observable universe expanding in total?
• What is the best estimate for the mass of the observable universe in kilograms?
• Why is it difficult to look at Mercury from Earth?
• Which three planets have rings?
• How long does it take Mercury to orbit the sun?
• Why do astronomers use light-years to measure distances to stars and galaxies?
• What happens to the intensity of solar energy as latitude increases?
• As apparent magnitude increases, a star's brightness will what?
• How can scientists determine the composition and temperature of stars?
• What does a red-shift in light tell us about the source? A blue-shift?
• What color are the coolest stars?
• What are some lunar surface features?
• Which color on the Torino scale is used to describe an object that will probably hit the Earth?
• What are some non-major (dwarf) planets?
• Why do constellations change position in the sky over a period of several months?
• What is the advantage of space based telescopes?
• How can a comet become the source of meteoroids and meteors?
• What is the state of most of the matter in the universe?
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• What is the coldest temperature ever recorded in the observant universe until now?
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• Do any scientist doubt the Copernican cosmology?
• Why did so many cultures pick out the same groups of stars in the sky to name as constellations?
• The Big Dipper constellation has been called many things by many different cultures. What are some of its other names?
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