Which of the following familiar objects is a star?
The sun is a star. It looks much brighter and larger than any other star, because it is much closer to Earth.
It takes approximately eight minutes for a photon of light to travel from the surface of the sun to Earth. What's the approximate distance between the sun and Earth?
A light-minute is the distance that light travels through a vacuum in one minute. Since it takes light approximately eight minutes to travel the distance from the sun to Earth, the sun is considered to be 8 light-minutes away. A light-minute is equal to about 1,117,694 miles (1,798,754 kilometers).
8 million miles
The process by which a star produces energy from hydrogen and other elements is called ___
Stars produce energy by way of nuclear fusion. Smaller atomic nuclei fuse together to produce larger nuclei, which not only release energy but also create different chemical elements. Most commonly, stars fuse hydrogen to produce helium, but the larger the star and the more its hydrogen is consumed, the more helium is fused into still heavier elements.
Which of these is true about the hottest type of stars, known as spectral type O, which shine blue-white?
They are much larger than our sun and take much longer to burn out.
They are much larger than our sun but they burn out much faster.
Stars of spectral type O are extremely large, but they burn out in just a few million years. By comparison, the sun, which is type G, has been shining for approximately 4.6 billion years and will be shining for billions of years to come.
They are smaller than our sun and burn out much faster.
Vega is one of the brightest stars in the sky. Why is it so bright?
It's a big star and very close to Earth.
Vega is a massive star that is about twice as large as our sun. It is only about 25 light-years from Earth, making it the fifth closest of all the bright stars. Its blue-white color is easily seen by the human eye.
It's really a white dwarf.
It's much older than our sun.
Which of the following is the most recognizable asterism (group of prominent stars that form a simple pattern) in the night sky?
The Big Dipper
All three are asterisms, but the Big Dipper is undoubtedly the most recognizable. It consists of seven bright stars that form the shape of a ladle. The Big Dipper is also useful for finding other stars.
Which of the following twinkles the most in Earth’s skies?
A simple way to remember: stars twinkle, planets don't. Twinkling is the result of the atmosphere distorting light and continuous, small changes in the distortion. When viewing light from a faraway star, it will seem like a point in the sky. In contrast, planets are much closer to Earth and look like discs rather than pinpoints.
Approximately how many stars comprise our galaxy, the Milky Way?
Galaxies range in size from dwarf galaxies containing around 100 million stars to mega-galaxies containing as many as 100 trillion stars. The Milky Way galaxy contains between 100 and 400 billion stars.
A friend asks you what’s the distance from Earth to the constellation Orion. Why is it not possible to give a definitive answer?
A constellation is a pattern that looks like a two-dimensional shape from our vantage point, but consists of stars located at varying distances.
A constellation only appears as a two-dimensional pattern as viewed from Earth. But in actuality, the stars are not all located at the same distance. So in the case of Orion, the distance from Earth to the stars ranges from 243 to 1,360 light-years away.
Constellations are so far away that astronomers cannot measure the distance to them accurately.
Orion is orbiting around Earth on an elliptical course, so its distance from us changes constantly.
Which of the following units is NOT a unit of distance across space?
A light-year is the distance that light travels through a vacuum in one year, equal to approximately 5.88 trillion miles (9.3 trillion kilometers). A parsec is approximately 3.26 light-years. An orbit is the course that one object takes around another object.
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