Download Light Years Lab

Name_____________________________________________ Date________________ Per___________
Light-Years Activity
Background Information: Use the information below to answer the questions below.
Distances in space are so vast that units like miles and kilometers are not practical. For example,
the distance from Earth to the star Proxima Centauri is 40 trillion kilometers. That’s 40 with twelve zeros!!
(40,000,000,000,000 km) Rather than trying to manage such large numbers, astronomers use light-years
to measure distances and sizes in the universe. A light-year is the distance light travels in one year: 9.5
trillion kilometers or approximately 6 trillion miles. By using light-years, the distance to Proxima Centauri
can be expressed as 4.2 light-years.
Evaluation Questions:
1. Which unit of measurement is easier to use when measuring distances and sizes in the universe,
light-years, miles or kilometers? ____________________________________
2. Why? __________________________________________________________________________
3. It is approximately 1 light year from the Sun to the edge of the solar system. If 1 light year = 6
trillion miles, how far is it, in miles, from the Sun to the edge of the solar system?
___________________ miles
4. How wide, in miles, is the Milky Way galaxy at 100,000 light-years across?
(1 light year = 6 trillion miles)
___________________________ miles
5. If 1 light year = 9.5 trillion kilometers, how wide, in kilometers, is the Andromeda galaxy at 200,000
light-years across?
________________________ kilometers
6. What’s the distance, in miles, between the Milky Way and the Andromeda galaxy if they are
2,300,000 light-years apart? (1 light year = 6 trillion miles)
___________________________ miles
7. On a clear night, you may be able to see the Andromeda galaxy, located 2.3 million light-years away.
How long did it take for the light from the stars in the Andromeda galaxy to reach your eyes?
_________________________________
Use the chart below to answer the questions that follow.
Star
Distance from Earth
A
B
C
D
55,000 light years
4,800 light years
105,000 light years
8,500,000 light years
(light years)
8. If all four stars exploded at the same time, which one would be the first to disappear from our night
sky? ________ Why? ______________________________________________________________
9. If all four stars exploded at the same time, which one would be the last to disappear from our night
sky? ________ Why? _______________________________________________________________
10. How far from Earth, in miles, is Star A? (1 light year = 6 trillion miles)
______________________________ miles
11. How far from Earth, in kilometers, is Star B? (1 light year = 9.5 trillion kilometers)
_____________________________ kilometers
12. If all four stars had same absolute brightness, which one would appear the brightest in our night
sky? _________ Why? ____________________________________________________________
13. How far, in miles, is Star A from Star B? HINT: subtract first!! (1 light year = 6 trillion miles)
______________________________ miles