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Quiz about Why So Sirius
Quiz about Why So Sirius

Why So Sirius? Trivia Quiz


What do you know about Sirius, the brightest star visible from Earth? Try this quiz and find out.

A multiple-choice quiz by StarGaGa. Estimated time: 4 mins.
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Author
StarGaGa
Time
4 mins
Type
Multiple Choice
Quiz #
366,017
Updated
Dec 03 21
# Qns
10
Difficulty
Tough
Avg Score
6 / 10
Plays
389
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Question 1 of 10
1. The origin of the name Sirius is the Greek word "seirios", meaning which of these? Hint


Question 2 of 10
2. Sirius is brighter in the night sky than the planet Jupiter. True or false?


Question 3 of 10
3. Sirius has how many companion stars? Hint


Question 4 of 10
4. With which other two bright stars does Sirius form an asterism, called the Winter Triangle? Hint


Question 5 of 10
5. What was the traditional duration of the "dog days" of the summer calendar in the Northern Hemisphere, associated with Sirius? Hint


Question 6 of 10
6. What is the stellar classification of Sirius? Hint


Question 7 of 10
7. Which of these reasons does NOT contribute to making Sirius the brightest star in the sky? Hint


Question 8 of 10
8. What is the mass of Sirius compared to our sun? Hint


Question 9 of 10
9. When is Sirius expected to exhaust its hydrogen and undergo helium flash, when it will burn the helium it has created as fuel? Hint


Question 10 of 10
10. According to astronomers, what will be the fate of Sirius? Hint



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Quiz Answer Key and Fun Facts
1. The origin of the name Sirius is the Greek word "seirios", meaning which of these?

Answer: scorching

Sirius was considered a scorching star. It rose for the first time each year in the pre-dawn sky in July and August, the hottest times of the year in the Mediterranean region. The Greek word for sun is helios or ilios, photra is fire, and phloga is flame.
2. Sirius is brighter in the night sky than the planet Jupiter. True or false?

Answer: False

The Moon, Jupiter, Venus, and Mars at closest approach are all brighter than Sirius.
3. Sirius has how many companion stars?

Answer: 1

Sirius B is a white dwarf. Its age has been calculated at 120 million years, and the two stars, forming a binary system, are calculated to be between 200 million and 300 million years old. It was discovered on January 31, 1862 through the lens of an 18.5-inch refractor, by Alvan Graham Clark and his father, telescope makers in Cambridgeport, Massachusetts.

They reported their finding right away to George Bond, head of the Harvard College Observatory. Professor Bond confirmed their discovery with Harvard's 15-inch refractor a week later, and reported the find to scientific societies in the United States and Europe. (Thanks to the University of Arizona's article about this discovery.)
4. With which other two bright stars does Sirius form an asterism, called the Winter Triangle?

Answer: Procyon and Betelgeuse

Procyon, in Canis Minor, the Little Dog, and Betelgeuse, the red giant in the right shoulder of Orion, form the Winter Triangle with Sirius. While all the others are nearby, they are too far away to form a distinctive, obvious triangle with Sirius.
5. What was the traditional duration of the "dog days" of the summer calendar in the Northern Hemisphere, associated with Sirius?

Answer: 40 days

In Homer's time, when the "dog days" were first identified, they extended 40 days from the last week of July till the end of the first week of September. This long spell of very hot weather was rumored to drive dogs crazy. Nowadays, the dog days are considered just the hottest days of August, whenever they might occur in any particular year.
6. What is the stellar classification of Sirius?

Answer: A0-1V

Sirius is an A-type star, temperature class 0, the hottest of the light blue or blue-white A stars. The 1V refers to its size, a subgiant.
7. Which of these reasons does NOT contribute to making Sirius the brightest star in the sky?

Answer: Size

Sirius is a mere 8.6 light years from our sun, it has a hot surface temperature and its apparent magnitude is -1.45, so all of these reasons contribute to its being recognized as the brightest star in our sky. Its size classification is subgiant, so it is much smaller than other very bright stars such as Betelgeuse and Antares, which are both M-class red supergiants.
8. What is the mass of Sirius compared to our sun?

Answer: 2 times our sun's mass

Surprisingly for such a bright, hot star, Sirius has just over twice the mass of our sun. It is expected to expend its hydrogen and convert to burning helium long before our sun, a steadily burning G-type star, exhausts its fuel supply.
9. When is Sirius expected to exhaust its hydrogen and undergo helium flash, when it will burn the helium it has created as fuel?

Answer: In about 700 million years

Sirius will remain in our sky as a bright blue-white A-type star for only about another 700 million years. Then it will start burning its helium for a short time.
10. According to astronomers, what will be the fate of Sirius?

Answer: White dwarf like Sirius B

Even though Sirius is currently two solar masses in size, above the Chandrasekhar limit for the formation of white dwarfs, astronomers are reasonably sure it will lose about sixty per cent or more of that mass as it goes through helium fusion, and becomes for a short time, a red giant.

As it cools it will then shrink and become a white dwarf like its companion. Sirius would need a current mass of 8 or more solar masses to become a neutron star or a black hole rather than a white dwarf. Stars significantly smaller than Sirius end their existence as brown dwarf stars.
Source: Author StarGaGa

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