Astronomy Practice
Two stars in the sky give off the same amount of total energy, but Star A appears 121 times fainter in our night sky than Star B. How many times farther away is Star A than Star B? (CH 5)
11 F = E / (4pi D^2) F = 1/121 E = 1 D = sqrt(E/F) = sqrt (1/1/121) = sqrt(121) = 11
If the Sun was moved father away and suddenly appeared 4 times fainter in the sky, how many times further away would it be? (CH 5)
2 F = E / (4pi D^2) F = 1/4 = 0.25 E = 1 D = sqrt (E/F) = sqrt (1/0.25) = sqrt (4) = 2
If the Sun were suddenly moved 5 times further away. How many times fainter would it be? (CH 5)
25
Star A is 200 times brighter than Star B. How many times hotter is Star A than Star B? (CH 6)
3.76 E = σT^4 (Ratio problem) E = 200 x's bigger T = (E) ^ (1/4) = 200 ^ (1/4) = 3.76
If the distance to a star was suddenly cut in half, how many times brighter would the star appear? (CH 5)
4 F = E / (4pi D^2) F = 1 / (0.5^2) F = 1 / 0.25 = 4
Sunspots are dark because they are ____ than the surrounding area. (CH 9)
cooler
Sunspots are caused by ... (CH 9)
magnetic fields
How many millimeters will a 17 mm wavelength radio wave be shifted if the source is traveling away from the observer at 12,000,000 m/s? (CH 8)
0.68 Δλ / λ = v / c λ = 17 nm v = 12,000,000 m/s c = 3 * 10^8 Δλ = λ * v/c Δλ = 17 * (12,000,000 / 300,000,000) = 0.68 Since Δλ is the change in lambda, this would be the amount that the radio wave is shifted. So the answer to this question is simply 0.68 nm
What is the peak wavelength of light coming from a star with a temperature of 2500 K? (Submit your answer in nanometers. Remember 1nm = 10^-9m) (CH 6)
1,160
If the peak wavelength of a star at rest is 350 nm, but astronomers on earth observe that it has been shifted by 2.25 nm. Then how fast is the star moving relative to the earth? (CH 8)
1,928,571 Δλ / λ = v / c λ = 350 mm Δλ = 2.25 nm c = 3 * 10^8 v = c * Δλ/λ v = 300,000,000 * (2.25 / 350) = 1,928,571 m/s
Description: The figure shows five stars (A -E) as they appear in the night sky from Earth. A darker shading is used to indicate the appearance of a dimmer star. Note that star B is shown the darkest, followed by D, C, E, and A. Rank the brightness (brightest = 1, faintest = 5) of each star as it appears in the night sky. (CH 9 EXTRA)
1. Star A 2. Star E 3. Star C 4. Star D 5. Star B
Description: The figure shows five stars (A -E) as they appear in the night sky from Earth. A darker shading is used to indicate the appearance of a dimmer star. Note that star B is shown the darkest, followed by D, C, E, and A. Rank the numerical value (greatest = 1, least = 5) of each star's apparent magnitude. (CH 9 EXTRA)
1. Star B 2. Star D 3. Star C 4. Star E 5. Star A
Description: The figure shows five stars (A -E) as they appear in the night sky from Earth. A darker shading is used to indicate the appearance of a dimmer star. Note that star B is shown the darkest, followed by D, C, E, and A. Assuming each star has the same luminosity, rank the distance (greatest = 1, least = 5) of each star from the Earth. (CH 9 EXTRA)
1. Star B 2. Star D 3. Star C 4. Star E 5. Star A
Description: The figure shows five stars (A -E) as they appear in the night sky from Earth. The absolute magnitude number is also provided to the right of each star. Rank the total amount of energy (greatest = 1, least = 5) begin given off by each star (CH 9 EXTRA)
1. Star C 2. Star D 3. Star E 4. Star A 5. Star B
Description: The figure shows five stars (A -E) as they appear in the night sky from Earth. The absolute magnitude number is also provided to the right of each star. Rank the distance (greatest = 1, closest = 5) of each star from Earth. (CH 9)
1. Star C 2. Star D 3. Star E 4. Star A 5. Star B
If the peak wavelength of a star at rest is 660 nm, but astronomers on earth observe that it has been shifted by 0.001 nm. Then how fast is the star moving relative to the earth? (CH 8)
454 Δλ / λ = v / c λ =660 nm Δλ = 0.001 nm c = 3 * 10^8 v = c * Δλ/λ v = 300,000,000 * (0.001 / 660) = 454 m/s
What is the peak wavelength of light coming from a star with a temperature of 5300 K? (Submit your answer in nanometers. Remember 1nm = 10^-9m) (CH 6)
547
If the peak wavelength of a star at rest is 550 nm, then what peak wavelength is observed when the star is traveling 150,000 m/s away from the Earth? (CH 8)
550.275 Δλ / λ = v / c λ = 550 nm v = 150,000 m/s c = 3 * 10^8 Δλ = λ * v/c Δλ = 550 * (150,000 / 300,000,000) = 0.275 Since Δλ is the change in lambda, this must be added or subtracted from the original λ. Since the star is moving away, it must be added. So the answer is 550 nm + 0.275 nm = 550.275 nm
The temperature at the surface of the sun is about ... (CH 9)
5700 K
What is the temperature of a star (in Kelvin) if its peak wavelength is 425 nm? (CH 6)
6,823 λmax = 0.0029 / T T = 0.0029 / λmax = 0.0029 / (425 x 10^-9) (be sure to use parentheses around the wavelength value) T = 6823 K
If the peak wavelength of a star at rest is 725 nm, then what peak wavelength is observed when the star is traveling 800,00 m/s toward the Earth? (CH 8)
723.067 Δλ / λ = v / c λ = 725 nm v = 800,000 m/s c = 3 * 10^8 Δλ = λ * v/c Δλ = 725 * (800,000 / 300,000,000) = 1.93 Since Δλ is the change in lambda, this must be added or subtracted from the original λ. Since the star is moving toward, it must be subtracted (blueshift). So the answer is 725 nm - 1.93 nm = 723.067 nm
The mass of the sun is composed of about ____ hydrogen. (CH 9)
75%
Star A is 3 times hotter than Star B. How many times brighter is Star A than Star B? (CH 6)
81 E = σT^4 (Ratio problem) T = 3 x's bigger E = (3)^4 = 81 x's bigger
Two stars appear the same brightness in the sky, but Star A is three times farther away than Star B. How many times more energy is Star A giving off than Star B? (CH 5)
9
Match each term with the appropriate definition (CH 7)
Scarp: A raised ridge on the surface of Mercury Regolith: Pulverized rock that covers the Moon as a fine dust Ray: A bright line emanating outward from craters Maria: Smooth dark regions on the Moon where lava once flowed Caloris Basin: A very large impact crater on Mercury
