This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 2/25/11 Extra Credit In today's Astronomy Picture of the Day, what kind of gas is in the glowing clouds? A. B. hMp://www.astro.psu.edu/users/cpalma/astro1h/class6.html Astro 109 Lecture 12: Our Solar System Feb. 25 C. D. E. Feb. 25 Quiz QuesRon #1 Which property is very similar for all planets in the Solar System? A. B. C. D. E. composiRon orbit shape and orientaRon rotaRon period size temperature Quiz QuesRon #2 Which of the following is not a characterisRc that disRnguishes Jovian from terrestrial planets? A. B. C. D. E. size number of moons mass composiRon orbital eccentricity Feb. 25 Feb. 25 Key Concepts Density and composiRon Terrestrial vs. Jovian planets Moons Asteroids, comets, Kuiper belt objects Discussion QuesRon Which of the following is not an observed paMern of moRon in our solar system? A. B. C. D. All planets orbit the Sun in the same direcRon. The orbits of the major planets lie nearly in a plane. Most planets orbit the Sun at the same speed. Most planets rotate in the same direcRon as their orbital moRon. E. Most moons orbit their planets in the same direcRon as the planets' rotaRon. Feb. 25 Feb. 25 1 2/25/11 MoRon Planets all orbit in the same direcRon, and in nearly the same plane. ProperRes Most rotate in that direcRon, too. Note: relaRve sizes are accurate; spacings are not to scale. Feb. 25 Feb. 25 How can we tell what they are made of? Solid / liquid / gas ? Rock / water / air How might we characterize the difference between them? Discussion QuesRon What informaRon can we use to determine the mass of Mars? A. B. C. D. E. The orbit of Mars around the Sun (orbital size and period). The orbits of Mars's moons (orbital sizes and periods). Mars's rotaRon period. The color of Mars's surface. The number of craters on Mars's surface. density = mass volume
g/cm3 2--3 1 0.0013 kg/m3 rock water Feb. 25 2000--3000 1000 1.3 air Feb. 25 Example: Mass of Mars Mars has two small satellites, Phobos and Deimos. Phobos circles Mars once every 0.31891 day at an average alRtude of 5980 km above the planet's surface. The diameter of Mars is 6794 km. R = 3397 km = 9377 km a = 3397 km + 5980 km Example: Density of Mars Mars has two small satellites, Phobos and Deimos. Phobos circles Mars once every 0.31891 day at an average alRtude of 5980 km above the planet's surface. The diameter of Mars is 6794 km. P = 0.31891 d = 27554 s 86400 s 1d R [P (s)] 2 M [a (km)] M (M ) 93773 -4 = 10 M 275542 5.974 1024 kg = 0.11 M M = 6.5 1023 kg = 10-4 3
Feb. 25 volume = = 3397 km 4 R3 3 3 4 = 3.397 106 m 3 = 1.64 1020 m3 6.5 1023 kg 1.64 1020 m3 = 3, 900 kg m-3 density = Feb. 25 2 2/25/11 Example: Density of Earth Mass = 5.971024 kg, diameter = 12,576 km, radius = 6,378 km volume = 4 R3 3 3 4 = 6.378 106 m 3 = 1.09 1021 m3 5.97 1024 kg 1.09 1021 m3 = 5, 500 kg m-3 Discussion QuesRon The average density of Earth is higher than that of typical rock. What does this suggest? A. Gravity from the Moon increases Earth's density. B. Earth's rotaRon increases its density. C. There must be a significant amount of ice under high pressure inside our planet. D. There must be a significant amount of material denser than rock inside our planet. E. Dirt is denser than you thought. density = Feb. 25 Feb. 25 DensiRes of the Planets Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Density (kg/m3) 5430 5243 5515 3934 1326 687 1318 1638 Mostly light elements (hydrogen, helium) Rocky, with dense iron cores A. B. C. D. E. Discussion QuesRon Which planet would float in water? Planet Earth Jupiter Saturn Uranus Neptune Density (kg/m3) 5515 1326 687 1318 1638 Feb. 25 Feb. 25 Jupiter's Galilean Satellites Feb. 25 Feb. 25 3 2/25/11 Jupiter's Moon Europa hMp://saturn.jpl.nasa.gov/science/moons/ Feb. 25 T B McCord et al. Science (1998) 280:1242-1245 Some excepRons to the paMerns Asteroids Feb. 25 Feb. 25 Main asteroid belt Comets Feb. 25 Feb. 25 4 2/25/11 Kuiper Belt Discussion QuesRon Many astronomers no longer regard Pluto as a true planet. Which of the following is the least persuasive reason for this view? A. Pluto's orbit is larger than that of any planet. B. Pluto's orbit is more eccentric than that of any planet. C. Pluto's orbit is more inclined to the plane of the solar system than that of any planet. D. Pluto is unusually small for a planet in the outer solar system. E. Pluto is quite similar to other Kuiper belt objects that have been discovered in recent years. Feb. 25 Feb. 25 Wikipedia Feb. 25 Feb. 25 Wikipedia Learning from diversity Why are the inner planets small and rocky, while the outer planets are big and gaseous? Why do some objects have atmospheres while others don't? What are rings? Why are some objects cratered while others are smooth? hMp://www.lunarplanner.com/asteroids-dwarfplanets/Eris.html What are the asteroids, comets, and Kuiper belt objects? Feb. 25 Feb. 25 Stay tuned! 5 ...
View Full Document
This note was uploaded on 03/24/2011 for the course PHYS 123 taught by Professor Wenkstern during the Spring '08 term at Rutgers.
- Spring '08