Homework Help for Astronomy

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Astronomy studies the objects and the physical phenomena of light-matter interaction in the outer space. From planets to the expansion of the Universe, Astronomy is one the most diverse areas of Physics.

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goldserval968 asked for the first time
in Astronomy·
30 Mar 2021
Verified Answer requested

For each problem, neatly show your work i ncluding equations used -- numerical answers only will not get full credit. Also, be sure to i nclude diagrams/sketches when requested. For numerical answers, i n general use 3 significant digits as you carry out your calculation. Also, for l arge (>1000) or small (<0.001) numbers, please use scientific notation and/or metric prefix. For example, i nstead of 0.0000103 meters, either report 1.03 x 10- 5 m, or 10.3 micro-meters (microns).


4. The following question will help us understand the concept of the Habitable Zone coming up i n Chapter 10. In the absence of clouds and greenhouse gases, we can approximate the surface temperature of a planet using the following

equation: TK = 300K  (Lsun1/4 ) /  (Rau1/2 ), where T k  is the temperature (in Kelvin) around a star with luminosity Lsun (in solar luminosities) at a distance Rau (in astronomical units).

a. [2pts] Imagine living on an Earth-like planet around a Brown Dwarf with only 1/1000 x the luminosity of the Sun. How CLOSE (in au) would your planet need to be to this star to have the same temperature as Earth around the Sun? (you can use the above equation to do the comparison).

b. [3pts] In about 5 billion years, the Sun will be a red giant and have 1000x higher luminosity! What will the equilibrium temperature of Earth be then? What will be the equilibrium temperatures of Jupiter's moon Europa and Saturn's moon Titan then?

c. [1pt] Do you think l ife might be possible i n our solar system when the Sun is a red giant, and i f so, which planets/moons? Justify your answer.

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plumantelope954 asked for the first time
in Astronomy·
29 Mar 2021

Astronomy Parallax Lab

SCENARIO: Your lab group is planning an expedition to measure the distance to Mars by carefully measuring its position in the sky from two locations simultaneously when it is next at “opposition” (that is, when it is exactly opposite from the sun in the sky) on October 13, 2020. For the best, and most straightforward distance determination with the parallax method, Mars should be high in the sky (as near to your zenith as possible).  This can be done by observing Mars: (a) from locations whose LATITUDES are similar to the DECLINATION of Mars at the date of measurement and (b) at the time of night when Mars is highest in the sky.

1a). Determine the Sky Coordinates of Mars on the date of opposition.  The relevant coordinate is the Declination (RA/DE J2000 coordinates should be used) – this is the sky coordinate analogous to Latitude on the Earth’s surface.  (Note, it is ok to determine these coordinates for Mars from anywhere on Earth for this initial measurement)

Mars DECLINATION on October 13, 2020: ___________________________

Your lab team needs to send observers to two cities that:

(a) have latitudes that are similar to the declination of Mars on that date (within 20 degrees); and

(b) have nearly the same longitude (that is, are nearly due North-South from each other (hint, you will need to go close to the equator!).

1b). Choose two of the cities below and use google maps, google earth or another online resource to record their names and Latitudes.

Melbourne, Australia Kampala, Uganda Tokyo, Japan
Omaha, NE, USA Mumbai, Italy Khartoum, Soudan

1c). At what time should you measure the sky coordinates (right ascension and declination) to get the most accurate possible parallax distance?

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