HW-3 Fall 2014
Homework Assignment #3
Due in class on Tuesday, Nov 4th
(10 pts each)
You are presented three meteorites that have the following densities:
5 g/cm3, (ii) 5.
5 g/cm3 and (iii) 7.
(a) Which ones could be undifferentiated?
(b) Which ones could be from the Kuiper belt?
(c) Which ones are most likely stony-irons?
(d) Which ones could be as old as 4.
56 billion years?
(e) Which ones might contain aminoacids?
(f) Which ones may be lunar?
(g) Which ones may contain Iridium?
NASAs mission WISE was launched in 2009 to survey the sky in infra-red.
principal investigator is UCLA Professor Ned Wright.
To do the mission, the spacecraft
required liquid Nitrogen (LN2) for cooling its detectors and peer far into the sky for distant
stars with high sensitivity.
Once the LN2 was consumed, the project turned its attention to
much brighter infrared objects in our planetary system that would still be observable without
LN2: asteroids and comets in the neighborhood of the Earth (Heliocentric distance < 1.
dubbed: near-Earth objects or NEOs.
Search the web on NEO-WISE and answer:
(a) How many new NEOs (Comets and Asteroids) did NEOWISE discover?
(b) Why is the information on the number and size of these NEOs useful?
(c) WISE also looks at distant dwarf stars, nebulae and dust.
It imaged the results of one
of the first recorded supernova explosion (1572AD by Tycho Brache).
This is seen as
a red blob at the top left of the image below.
(Note: An explosion like this one may
have started the accretion of our own solar system).
Tychos supernova cloud is (still)
expanding at 9,000km/s as measured from Doppler shift measurements today.
the age of the supernova and assuming a constant cloud expansion speed what is the
clouds diameter, in AU, and about how many times the diameter of Neptunes orbit is
HW-3 Fall 2014
(a) Compute the volume ratios of Sun to Jupiter and of Jupiter to Earth using the
ratios of the planetary radii.
It is OK to use approximate values like 100:10:1 instead of
[But you can also use the actual values from the appendix in your book].
(b) Use Newtons form of Keplers 3rd law along with G=6.
673x10-11 Nm2/kg2 to
compute the Sun-to-Jupiter mass ratio, and the Jupiter-to-Earth mass ratio.
To do so,
compute the masses using G and then take the mass ratios.
- the mass of the Sun from the orbit period of the Earth [1 year, 1AU; make sure you
translate units in seconds and m]
- the mass of Jupiter from the orbit of Europa [period = 3.
551 days, distance = 671,000km]
- the mass of Earth from the acceleration of gravity [g=9.
(c) Compare the volume ratios to the mass ratios.
What do those tell you about the
similarities or differences in density and composition between Sun, Jupiter and Earth?