Astro 1500 Trivia February 21st

What is the correct ranking of astronomical objects in order of decreasing size?

• Sun, Solar System, Milky way, Supercluster

• Milky way, Solar System, Sun, Supercluster

• Sun, Solar System, Supercluster, Milky Way

• None of these answers

Answer explanation

The correct ranking would be, supercluster, milky way, solar system, sun

The dwarf planet Ceres takes 4.6 years to orbit the sun, how far away from the Earth is it, when the Sun, Earth and Ceres are all aligned?

• 2.8 AU

• 9.8 AU

• 1.8 AU

• 8.8 AU

Answer explanation

The orbital period of ceres is 2.8 AU, that is, 2.8 AU away from this sun. The earth is 1 AU away from the sun to 2.8-1=1.8.

Star A is 4 times as luminous and 2 times farther away than Star B, how do their brightnesses compare?

• Star A is 4 times brighter as star B

• Star A is 2 times brighter as Star B

• Star A and Star B are the same brightness

• Star B is 2 times brighter than Star B

Answer explanation

Show on whiteboard

We can see optical light from the ground. Why then do we have some optical telescopes

(such as Hubble) in space?

• To get above the atmosphere

• They are cheaper to build

• To get away from noise pollution

• All of the above

Answer explanation

Noise pollution has little to no effect on telescopes, and space based telescopes are much more expensive, so the correct answer is to get out of the atmosphere

Let’s say that you build your own radio interferometer consisting of two dishes. You move the dishes further apart. In doing so, does the light gathering power change or stay the same? If it changes, how does it change?

• No, the light gathering power doesn't change

• Yes, the light gathering power changes and it gets better

• Yes, the light gathering power changes and it gets worse

Answer explanation

Moving the telescopes does not change the light gathering power, you would have to make the telescopes larger

Which of the following is a big disadvantage to ground-based telescopes?

• Useful all year round

• Limited access to the entire EM spectrum

• Built below the atmosphere

• Relatively inexpensive

Star A has a temperature of 8,000K and Star B has a

temperature of 4,000K. Star B also has a radius that is 4 times the size of Star A. What is

the ratio of the peak wavelength of emission for Star A to Star B?

• 4

• 1/4

• 2

• 1/2

Answer explanation

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Which of the following types of photons have the highest energy?

• Blue light

• Ultraviolet Light (UV)

• Infrared Light (IR)

• Red light

Answer explanation

UV has a lower wavelength, therefore higher frequency, therefore higher energy

If humans are blackbodies, and blackbodies emit radiation at a large range of wavelengths, why are we not obviously glowing in the visible range?

• Because all of our light comes out as infrared light and at no other wavelengths.

• We don't actually emit radiation at any wavelength.

• We peak in the infrared, but only emit a very small amount of visible light

• This is still a mystery to scientists and we are still trying to figure it out

Answer explanation

Although we technically emit a very small amount of light in the visible range, it is almost nothing, so we don't see it

What could be responsible for absorption lines we see from a far away star?

• The star's atmosphere

• A could of hydrogen in-between us and the star

• Earth's atmosphere

• All of the above

Answer explanation

Any of these could absorb sections of the blackbody radiation