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ASTR178 Other Worlds Week 2, August 11. A/Prof. Orsola De Marco 9850 4241 orsola.demarco@mq.edu.au http://www.physics.mq.edu.au/current/undergraduate/units/ASTR178/. The Moon practical.
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ASTR178Other WorldsWeek 2, August 11 A/Prof. Orsola De Marco 9850 4241 orsola.demarco@mq.edu.au http://www.physics.mq.edu.au/current/undergraduate/units/ASTR178/
The Moon practical • The first day when you can go out and look at the moonin the early evening is the 14th. DO NOT WAIT to do thepractical at the last minute as the Moon does not wait foryou.
Remember! • Lecture notes for Week 1 and 2 are up on Blackboard. • Assignment 1 has been posted. Due back Fri 13th by 4PM in the assignment boxes. It will be returned in class on Mon 23 and Tue 24 August. Help questions (For this class) • 5,10 page 124. 26, page 125. 45-47, page 126. • 1-6 page 180. 7, 9-21 page 181.
In last class • Galileo and his observations – the phases of Venus. • Newton and gravity. • Tides. • Lunar phases. • Lunar and solar eclipses.
In this class • A few words on the Sun to start a tour of the Solar System. • What is light. • Comparing the planets. • The density of the planets. • The largest “satellites”. • What are planets made of. • The planetary atmospheres • The outer solar system. • Craters, volcanos and magnetic fields.
The eclipsed moon is red for the same reason why the sky is blue and the sunset is red!
Angular and Linear size • Unexaminable • The angular size of the Sun and Moon are very similar! • This allows us to study the solar corona. • Linear size = Distance x sin (angular size) • d = D sin (q) • Distance to the Sun = 150 million km • Distance to the Moon = 400,000 km • Sun’s radius = 6.9 x 1010 cm • Moon’s radius = 1700 km = 1.7 x 108 cm • so …
The Sun (Alexei Gilchrist will deal with the Sun in depth – this is just a very short intro)
Light is not only visible light.We call light atany wavelength: electro-magnetic radiation
The concept of temperature: A body with temperature emits electro-magnetic radiation (light). Hotter bodies emit more light at higher energy = shorter wavelength (ultraviolet). A cooler body emit more light at lower energy = longer wavelength (infrared).
The planets and the Ecliptic • All planets orbit the Sun approximately on one plane. • From the point of view of Earth the Sun and planets all move on the same plane, called the Ecliptic. Clementine Spacecraft
The seven giant moons in the Solar System Mercury drawn to the same scale Why do some planets have satellites and others do not?
From spectroscopy we know that Titan’s atmosphere is made of methane and N2
Gas giants: H2 and He • Gas, liquid and solid form. • Cold on their surface. • What dictates what is • In a planetary atmosphere?