Download What is the minimum size of a star that will go supernova? A. Half

What is the minimum size of a star that will go supernova? A. Half the mass of the Sun B. Eight times the mass of the Sun C. Twice the mass of the Sun Answer: B. Eight times the mass of the Sun Stars with less than 8 times the mass of the sun will end their lives as a white dwarf. In how many years will the sun enter the red giant phase of its life? A. 5 million B. 5 billion C. 5 thousand Answer: A. 5 billion The sun is roughly half way through its life. On average, how frequently do supernovas occur in a galaxy the size of our Milky Way? A. 500 years B. 50 years C. 5,000 years Answer: B. 50 years While stars large enough to go supernova are rare, there are so many stars in the Milky Way that supernovas occur fairly often. What percentage of stars end their lives as white dwarfs? A. 97% B. 10% C. 53% Answer: A. 97% Most of the stars in the galaxy are not large enough to end their lives with a supernova. Which two phenomena are possible end results of a supernova? A. Black hole or planet B. Black hole or neutron star C. Neutron star or white dwarf Answer: B. Black hole or neutron star If a star is 8‐20 times larger than the sun, it will end up as a neutron star. Anything larger will turn into a black hole. Which star will live longer a blue giant or a brown dwarf? Answer: Brown dwarf The cooler the star, the slower it burns through its fuel and the longer it will live. In 1975, Jill Tarter coined the name for this type of star, which ranges in size from 13‐75 times the mass of Jupiter. A. Brown dwarfs B. Red giants C. Yellow stars Answer: A. Brown dwarfs Brown dwarfs are very cool stars, some only slightly warmer than a BBQ grill. In the distant future, when the sun is a red giant, it will increase in size until it engulfs the inner solar system to which planet? A. Earth B. Mercury C. Jupiter Answer: A. Earth As the sun ages, its gravity will decrease, causing the sun to puff out. It will puff out to the radius of the Earth’s orbit. “Twinkle, Twinkle Little star,” why do you twinkle where you are? A. The Earth’s atmosphere causes the twinkle B. The star itself causes the twinkle Answer: A. The Earth’s atmosphere The atmosphere of the Earth causes the light that enters it from space to be slightly distorted. This distortion causes the stars to look like they twinkle. Every black hole has a boundary where the escape velocity, or how fast something must travel to leave the black hole, is greater than the speed of light. What is the name for this boundary? A. Event horizon B. Far horizon C. Black hole horizon Answer: A. Event horizon Once light enters the event horizon, it cannot escape and "falls" into the black hole. Which force keeps globular clusters, groups of hundreds of thousands of stars that orbit the core of the galaxy as a group, together? A. Gravity B. Radiation pressure Answer: A. Gravity The gravity from all the stars in the cluster gently pull on each other keeping the cluster together. In the fusion process that fuels stars, hydrogen turns into which other element? A. Helium B. Carbon C. Iron Answer: A. Helium In fusion, hydrogen atoms join together to form helium plus energy. Supernova enrich space with newly created elements. Are the elements of a higher or lower mass than hydrogen? A. Higher mass B. Lower mass Answer: A. Higher mass All elements with mass higher than iron are created by supernova. Spots on the surface of stars, called star spots, are areas of the surface where the temperature is different from the rest of the star. Is the temperature of these spots higher or lower than the rest of the star? Answer: Lower Astronomers are not sure what causes these cooler spots, but the spots often have a more intense magnetic field. Stars are formed in large clouds of gas, occasionally referred to as “stellar nurseries.” Which of these is an example of a stellar nursery? A. Galaxy B. Nebula C. Super cluster Answer: B. Nebula A nebula is a large cloud of gas in space. These clouds are both the starting point and ending point for many stars during their evolution. The hotter the star, the longer or shorter it’s lifetime Answer: Shorter Hot stars live fast and die young. The hotter the star, the faster that it turns hydrogen into helium and the shorter its life. Which of these objects is the closest stellar nursery to the Earth? A. Orion Nebula B. Ring Nebula C. Horsehead Nebula Answer: A. Orion Nebula The Orion nebula is a little more than 1300 light years away. The Ring Nebula is a planetary nebula, formed at the end of a star’s life. True or False: It is possible to directly observe a black hole. Answer: False Black holes have so much gravity that light cannot escape them. Because of this, astronomers cannot observe them directly. Rather, they look for evidence of black holes. Evidence of a black hole includes a group of stars moving around a region of space that looks empty or gas falling to a black hole. Right before the gas enters the black hole, it releases radiation that can be detected from Earth. Two forces battle for dominance within a star, gravity and radiation pressure. When the forces balance, the star is stable. If gravity is pulling inward towards the center, in what direction is radiation pressure acting? Answer: Pushing away from center Without radiation pressure, the gravity of the star would cause the star to collapse. A planetary nebula, an expanding shell of gas and plasma, forms around the core of a star between which two stages? A. Red giant and white dwarf B. Red giant and brown dwarf C. White dwarf and brown dwarf Answer: A. Red giant and white dwarf A white dwarf is the left over carbon core of a star. It’s essentially a very hot diamond. Which of the following terms is defined as a cataclysmic explosion of a star? A. Supernova B. Quasar C. Sun Answer: A. Supernova When a star goes supernova, the gravity of the star causes the star to collapse. When this happens, a tremendous amount of energy is released. Some stars have the same name, but are differentiated by a letter, like Sirius A and Sirius B. Why do astronomers do this? A. The stars are binary B. Different people discovered the stars at the same time C. Astronomers have run out of names. Answer: A. The stars are binary Usually the brighter of the two stars is discovered first, resulting in the fainter star having the letter B. Astronomers study light from stars to determine their age, temperature, and distance. What is this type of study called? A. Lumascopy B. Astroscopy C. Spectroscopy Answer: C. Spectroscopy A spectroscope uses a prism to break the star’s light into a rainbow. An astronomer can use this rainbow to determine almost everything about the star. Some stars have a companion star and the two orbit around each other. What are these star systems called? A. Trinary B. Globular C. Binary Answer: C. Binary If more than two stars are in orbit around each other, it’s called a multiple system. True or False: There are more stars in the universe than grains of sand on all the beaches on Earth. Answer: True Astronomers have not discovered all the stars in the universe, but at current estimate there are 200 billion billion MORE stars than grains of sand. True or False: White dwarfs are the final evolutionary state for the majority of the stars in the Milky Way. Answer: True Most stars in the Milky Way are not large enough to go supernova. 97% of stars end up as white dwarfs True or False: A white dwarf is the size of the Earth, but closer to the mass of the sun. Answer: True A white dwarf is the very dense core of a star like the sun. True or False: When a white dwarf becomes more than 1.4 times as massive as the sun, it can go supernova. Answer: True This limit is known as the Chandrasekhar limit. When the white dwarf surpasses this limit, it explodes into a Type Ia supernova. All stars end their lives as supernova. Answer: False Less than 3% of all stars end their life as supernova. True or False: Red giants are stars that are nearing the end of their lives. Answer: True Red giants are in the second to last stage of their evolution. From here, they will become white dwarfs True or False: The sun's next evolutionary stage is as a white dwarf. Answer: False The star will first evolve into a red giant, before ending its life as a white dwarf. True or False: All stars are the same color. Answer: False The color of a star depends on the temperature of the star. The coolest stars, brown dwarfs can have temperatures similar to BBQ grills. The hottest stars can have temperatures close to 50,000 degrees. True or False: Red giants evolve from stars between 0.5‐8 times the mass of the sun. Answer: True Stars larger than 8 solar masses will go supernova. Stars smaller than 0.5 solar don’t evolve past their current stage. True or False: All stars end up as black holes. Answer: False Before a star becomes a black hole, it must undergo a supernova. Less than 3% of stars will go supernova, so the majority of stars will not end up as a black hole. True or False: A black hole has a gravitational field so dense that not even light can escape it. Answer: True Black holes have so much mass in such a small space that their gravity is strong enough to keep light from escaping True or False: All black holes are the same size. Answer: False Astronomers theorize that there are four different sizes of black holes: supermassive or hundreds of millions of times the size of the sun, intermediate or thousands of times the size of the sun, stellar or 3 times the size of the sun, and micro, much smaller than the sun. Astronomers have never detected micro black holes, but they can exist in theory. True or False: Yellow stars like the sun are rare. Answer: False 1 in 13 stars are similar in color to the sun. Compare that to blue stars where only 1 in 3 million exist. True or False: Blue colored stars are hotter than red stars. Answer: True A red star has a surface temperature of 3000‐5000 degrees, but a blue star can be as hot as 50,000 degrees. Which type of star no longer creates its own energy? A. White dwarf B. Blue giant C. Red giant Answer: A. White dwarf A white dwarf is the leftover cooling core of a star. It gives off light as it cools, but can’t produce its own energy. Which one of these types of stars is NOT an ending point of stellar evolution? A. White dwarf B. Brown dwarf C. Neutron star Answer: B. Brown dwarf Brown dwarfs are very small, very cool stars. Brown dwarfs occupy the mass range between which other two astronomical bodies? A. White dwarfs and red giants B. Gas giant planets and small mass stars C. Moons and planets Answer: B. Gas giant planets and small mass stars The smallest observed brown dwarf is 13 times the size of Jupiter. True or False: A closer, but cooler red star can appear brighter to people on Earth than a farther, but hotter blue star. Answer: True Stars that are closer to the Earth appear brighter in the night sky. It’s very possible for a close red star to appear brighter than a far blue star even though it’s cooler. Which heavenly body is known as both the morning and evening star? A. Venus B. The Moon C. Sirius Answer: A. Venus Venus (with a close orbit around the sun) appears as the first bright object either after sunset or before sunrise. True or False: The north star is the brightest star in the sky. Answer: False Polaris or the north star is not the brightest star in the sky. Its significance comes from the fact that it appears to lie above the Earth’s North Pole. This causes it to appear to remain stationary, marking north. True or False: The north star changes over time due to the wobble of the Earth. Answer: True The Earth slowly wobbles like a top. Due to this wobble, over tens of thousands of years, the star that marks the north pole changes. A shooting or falling star is a: A. Star B. Airplane C. Meteor or rock from space Answer: C. a meteor or space rock As the meteor enters the Earth’s atmosphere, it heats up causing a glowing streak in the sky. True or False: A supernova will occur in our Milky Way galaxy during your lifetime. Answer: True Supernova or an explosion of a star occur on average of every 50 years in a galaxy like ours. If you think of the sun’s lifetime like a person’s, the sun would be a: A. Baby B. Middle aged adult C. Senior citizen Answer: B. Middle aged adult The sun is 5 billion years old, about half way through its life. Name the star closest to the Earth. Answer: The Sun The sun is the closest star to the Earth. Astronomers use light years to measure: A. Distance B. Time Answer: A. Light years measure the distance light travels in one year Light travels 5.8 Trillion miles in one year. How far away is the sun from the Earth? A. 93 thousand miles B. 93 million miles C. 93 billion miles Answer: C. 93 billion miles It takes the light from the sun 8 minutes to reach the Earth. Which star will have a longer life, a hot star or a cool star? Answer: A cool star The hotter the star, the faster it burns through its source of fuel, hydrogen. Hot stars live fast and die young. What are stars? A. Massive balls of gas B. Massive balls of lava C. Massive balls of fire Answer: A. Massive balls of gas Stars are made up of very, very hot gas. So hot in fact, that the gas is called plasma. Stars are made up primarily of which two elements? A. Uranium and lead B. Plutonium and argon C. Hydrogen and helium. Answer: C. Hydrogen and helium Hydrogen is the most common element making up 75% of the universe. If we look at the star Sirius, which is 10 light years away, do we see Sirius as it looks today or as it looked 10 years ago? Answer: 10 years ago It takes that long for the light from Sirius to reach us. That makes the universe like a time machine, we always see things as they were, not how they are now. True or False: The stars in the constellations are close to each other in space. Answer: False In most constellations, the stars just appear to be close together because of how we see them on the Earth. They’re actually separated by many, many light years. Which is denser, a tablespoon of the Earth or a tablespoon of a black hole? Answer: A tablespoon of black hole A black hole is so dense that not even light can escape it. Which two constellations never go below the horizon if you live in the northern United States, Canada or Alaska? A. Orion and the Big Dipper B. The Big Dipper and Cassiopeia C. Orion and Cassiopeia Answer: B. The Big Dipper and Cassiopeia Both constellations lie in the sky very close to the Earth’s north pole. While they move around the pole throughout the year, they never set. Many stars have names from this culture, one that was on the cutting edge of astronomy for many centuries. A. Arabic B. American C. Hawaiian Answer: A. Arabic The ancient Arabs were great astronomers and named many of the brightest stars in the sky. The names were then translated into English. True or False: A person can use the stars to find their way. Answer: True You can find north by locating the North star. Ancient Polynesians traveled all over the Pacific using only the stars to guide them. Which element is the most common in the universe? A. Oxygen B. Iron C. Hydrogen Answer: C. Hydrogen Hydrogen makes up 75% of the universe. Which star is the faintest star in the Sun’s neighborhood? A. Sirius B. Giclas 51‐15 C. Barnard’s Star Answer: C. Gicias 51‐15 This star’s, a red dwarf, is only 0.1% as luminous as the Sun. One of the closest stars to the sun, this red star flares, causing it to increase in brightness over a matter of minutes. A. Proxima Centuari B. 61 Cygni A C. Epsilon Indi A Answer: A. Proxima Centuari Located roughly 4.5 light years from the sun, this star takes over 1 million years to orbit Alpha Centuari A and B. All of the stars named Ross, Wolf or Luyten have two things in common. What are they? A. They are all red dwarfs named after their discoverers. B. They are all red dwarfs with planets around them. C. They’re all yellow stars named after their discovers Answer: A. They are all red dwarfs named after their discoverers. Frank Ross, Max Wolf and Willem Luyten all cataloged nearby stars in the early part of the 20th century. Two of the nearest brown dwarfs to the Sun combined with an orange star make up which multiple star system? A. Alpha Centuari A B and Proxima Centuari B. Luyten 789‐6 A,B,C C. Epsilon Indi A,B,C Answer: C. Epsilon Indi A,B,C Epsilon B and C are brown dwarfs that require about 70,000 years to orbit Epsilon A. The brightest star within 15 lights years to the sun is: A. Sirius A B. Tau Ceti C. Ross 154 Answer: A. Sirius It is the brightest star within 25 light years of the sun. Sirius B, the companion star to Sirius A is what type of star? A. Brown dwarf B. White dwarf c. Red dwarf Answer: B. White dwarf Not only is Sirius B a white dwarf, but it was the first white dwarf ever discovered in 1852. Tau Ceti, the closest yellow star to the sun was one of the early stars that SETI astronomers looked at for evidence of what? A. Intelligent life B. Black holes C. Wormholes Answer: A. Intelligent life SETI or the search for extraterrestrial intelligence searched around Tau Ceti and Epsilon Eridani in 1960 for evidence of intelligent life. They didn’t find it. This white star with twice the Sun's diameter is the largest, but not the brightest, star within 25 light years of Earth. A. Alpha Centuari A B. 61 Cygni A C. Procyon A Answer: C. Procyon A With a diameter twice the size of the sun, this whitish yellow star is the largest star within 25 light years of the sun. The brightest star however is Sirius. Barnard’s Star has the highest proper motion of any star in the sky. What is proper motion? A. Very polite motion from a star B. Angular change in position by a star as seen from Earth C. The correct motion of a star Answer: B. The angular change in position by a star as seen from Earth. Stars appear to have fixed positions on the sky. That’s one reason why the constellations are the same year to year. Stars that are close to the Earth however appear to move a small amount relative to the other stars in the sky. This star, whose name means “Female Warrior,” is not only part of the constellation Orion, but was also a villain in the Harry Potter books. A. Bellatrix B. Vega C. Castor Answer: A. Bellatrix The star that’s the right hand of Orion means "female warrior" in Greek. Bellatrix is a hot blue star with a surface temperature of 20,000 degrees. It’s located 240 light years from Earth. This red giant, one of the largest and brightest stars known, lies in the constellation Orion. Be careful not to say its name three times though or you could end up in trouble. A. Pollux B. Gemini C. Betelgeuse Answer: C. Betelgeuse It lies 640 light years from Earth. Betelgeuse’s radius is so large that if placed in our solar system, its surface might extend to between the orbits of Mars and Jupiter. This open cluster, frequently known as the seven sisters because of its seven bright stars, can be found on the logo of the Subaru car company. A. Pleiades B. Duck Cluster C. Princess Cluster Answer: A. Pleides Lying 440 light years from Earth, the Pleides is 60 million years old and dominated by young, hot blue stars. The stars are loosely bound together by gravity. Astronomers estimate that in another 250 million years however, the stars in the cluster will have gone their separate ways. Astronomers call this star “the most important star in the sky next to the sun.” Science fiction fans know it as Ellie Arroway’s destination in the movie and book, Contact. A. Lyra B. Rigel C. Vega Answer: C. Vega Vega is one of the most closely studied stars next to the sun. It serves as the basis for one of the brightness scales that astronomers use to measure stars. Although it’s 25 light years from the Sun, astronomers have been able to detect at least one planet orbiting Vega. A large explosion on the surface of the sun, much like a burp, is called: A. a solar flare B. a sun spot C. a rainbow Answer: A. Solar flare This explosion of energy can cause damage to satellites. It also causes the Northern lights. True or False: 61 Cygni is a binary star system Answer: True It is made up of Cygni A and B. Both stars are orange, but take 700 years to orbit each other. True or False: Stars give off radio signals. Answer: True Stars give off energy that can be heard using radio telescopes. The sun sounds a lot like static with a faint pattern in the radio. True or False: Red dwarfs are larger than the Sun. Answer: False The largest red dwarfs have a mass less than half that of the sun. True or False: Most of the stars within 12 light years of the Sun are hot, blue stars. Answer: False Most of the stars close to the Sun are red, dwarfs. The closest hot blue star to the sun is Spica, 260 light years away. True or False: Stars are categorized by their temperatures. Answer: True Stars are classified by how hot their surface temperatures are. Astronomers use spectroscopy, the study of light, to determine the star’s temperature. True or False: Stars don’t spin like planets do. Answer: False Stars spin like planets. But unlike planets, the equator of the star takes longer to rotate than the poles. The rotation rate of the sun’s equator is 25 days. In the newest Star Trek movie, a supernova threatens to destroy life in the galaxy. Is this really possible? Yes or no Answer: No While supernova are huge explosions, that can out shine a galaxy, only planets within 50 light years will likely be affected by the explosion. Astronomers theorize that when a supernova results in a black hole, a narrow beam of very intense radiation is emitted. This beam is called a: A. Gamma ray burst B. Zeta ray burst C. Event horizon Answer: A. Gamma Ray burst Gamma ray bursts are extremely hard to study. They typically last only a few seconds and only occur a few times in a galaxy over a million years. Gamma rays are not detectable from Earth, but the SWIFT satellite in space detects them and alerts astronomers when a burst occurs. In the nineteenth century, Charles Messier made a catalog of objects that could be seen with the naked eye. Astronomers refer to these objects using a letter and number. What letter do they use? C, M or Q Answer: M The objects are known as Messier objects. To shorten Messier 1, astronomers will refer to it as M1. M1 is also known as the Crab Nebula. At the beginning of the twentieth century, this Harvard astronomer developed a new method that was a big jump in the classification of stars. A. Henrietta Swan Leavitt B. Jocelyn Bell C. Annie Jump Cannon Answer: C. Annie Jump Cannon In 1896, the director of Harvard’s observatory, Edward Pickering, decided to hire women to perform data reduction and carry out calculations. Building on the work of others, Cannon simplified the system of classifying stars. She also discovered over 300 stars. True or False: Rapidly spinning stars that give off regular pulses of radio signals are called quasars. Answer: False These stars are called pulsars. They are the remnants of supernova. Quasars are jets of energy that are caused by super massive black holes at the center of distant galaxies. Quasars is short for quasi‐stellar object. True or False: All galaxies are the same Answer: False All galaxies are made of stars, but in most cases, that’s where the similarities end. There are two main types of galaxies, spiral and elliptical. Spiral galaxies are younger and full of star forming regions. Elliptical galaxies are older and may be the result of galaxy collisions. True or False: Astronomers can use the moon to measure the diameter of some stars. Answer: True If astronomers know the distance to a star, they can use how length of time that the moon eclipse the star to determine its diameter. They use trigonometry to do this. The population density of stars increases towards the center of the galaxy. However, the center of the galaxy does not appear brighter from Earth. Why is this? A. The star light is blocked by gas and dust B. The star light is blocked by aliens C. Dark matter Answer: A. The star light is blocked by gas and dust Our eyes are not capable of seeing the light from the stars in the center of the galaxy because of all the gas and dust. Astronomers need to use infrared cameras to see stars in the center of the galaxy. How many stars are in our Milky Way? A. Less than one million B. Less than one billion C. Hundreds of billions Answer: C. Hundreds of billions In a really dark place, a person could see around 2000 stars in the night sky. However, astronomers estimate that our galaxy has anywhere from 100‐
400 billion stars. True or False: Globular clusters are groups of hundreds of thousands of stars that orbit above and below the center disc of the galaxy Answer: True Around 160 known globular clusters orbit our Milky Way. These clusters contain some of the oldest stars in our galaxy. Astronomers have a different view of metals than everyone else. What do astronomers consider a metal? A. Elements heavier than helium B. Everything C. Elements heavier than plutonium Answer: A. Elements heavier than helium Astronomers consider all but two elements, hydrogen and helium, metals. These two elements combined make up around 98% of the universe. Because astronomers study the entire universe, its easier to call everything that isn’t hydrogen or helium a metal. Stars that change in brightness over a period of time are called: A. Changing stars B. Variable stars C. Einstein’s stars Answer: B. Variable stars There are three categories of variable stars. The first, pulsating variables, change in brightness because the star changes size over a period of time. The second, eruptive variables, change in brightness because of flares or ejection of stars. The last category are stars that only appear to change in brightness, but in actuality, another star eclipses them.