Class Notes (806,585)
Canada (492,337)
EPSC 201 (116)
Lecture 4

EPSC201 Lecture 4 Notes.doc

6 Pages
Unlock Document

McGill University
Earth & Planetary Sciences
EPSC 201
Anthony Williams- Jones

EPSC201 - Lecture 4 Notes Creating a galaxy and creating a solar system are similar. The disk of mass is rotating; the gravity pulls the mass to- wards the center, which forms a sun or a black hole. The rings spinning around the sun will become the planets. There are separate rings. The larger particles are dragging in the smaller ones, which makes them even bigger. These particle clumps are called partitesimals. The composition in each each ring will be different. The ring is colder on the outside, hotter on the inside. That makes certain gases con- dense at different distances. Olivine and iron condense around 1800 Celcius which forms metallic iron and olivine. The snowball goes around and gathers more dust, making planet earth. Going further out, the tempera- ture drops lower, making water vapour condense into liquid and ice. Carbon dioxide become solid at -56 Celsius and is dry ice. Methane be- comes solid at -182 Celsius. Ammonia is also a composition of the gas planets. The gas planets are actually not gas, but solids that would be gas on Earth. The inner core of gas giants con- tain elements that would be on earth, such as iron and olivine. The lighter elements like methane and wa- ter are on the surface, and make up a large part of the planet. If the object is fairly small, it will have an odd potato shape. The larger it is, the more gravity there is to pull it into a sphere. Gravity slowly shapes the object into a sphere. Planets are effectively spherical, some of the smaller moons on Mars and Jupiter are not spherical. Io, one of the moons of Jupiter, is the most active ob- ject in our solar sys- tem. There is lots of volcanic activity. Almathea, formed 4.6 billion years ago, has craters because the surface is not active like Io is. Almathea is also a moon of Jupiter. Earths Moon has not had much volcanic activity for about 3 billion years. Our moon is the result of the collision of Earth with another object about the size of Mars, the heavier parts of the incoming planet joined into the Earths core, and the outer part of the Earth got melted along with the lighter parts of the incoming planet. A lot of the material got put into orbit, which eventually be- come the moon. The force of gravity took over and snowball effected. Points of Evidence 1. The Moon does NOT have an iron core, it is much less dense then the Earth. If you exclude the core of Earth, the densities are similar. Both about 3.1 g/mL dense. THE MOON DOES NOT HAVE A CORE 2. The isotopic ratios of the Moon and Earth are the same. Earth also has lots of material from Mars due to meteorites. It is isotopically different then Earth and lunar material. This also supports the collision theory for the formation of the moon. Pluto was demoted in 2006 from a planet to not. Its orbit does not fit in line with the disk orbit of the other planets. It is now officially a dwarf planet. Pluto has five moons. It now joins other dwarf planets in the Kuiper belt. Planet Earth: Iron and Oxygen dominant the chemical composi- tion of Earth. In the core there is a lot of Iron and Olivine (Fe,Mg)2SiO4 Olivine has lots of oxygen. Magnesium and silicon are part of olivine. The Composition of the Crust: The crust varies from 6-70 km deep, which isn’t that deep. A good analogy of the Earth is that it is like an egg. The yolk is the core. The shell is the crust. and the egg white is the mantle. The outside is brittle, but the inside is ductile like a hard boiled egg. Iron core, olivine surrounds core. The core is the most dense part of the earth, 15 g/mL. The mantle is much less dense, about 3.3 g/mL . Professor said not to memorize numbers, just have a rough idea. The outer crust is much less dense the the core, about 2.5 g/mL. Volcanoes give clues about the composition of the mantle. Volcanoes can go up to a couple hundred km, melting grabs a piece of mantle and brings it up to the surface. These pieces are called xenoliths. (for- eign bits of rocks) The volcano is erupting foreign pieces of rock from the mantle. A good example is dia- monds. Diamonds come from considerable depth in the mantle. They come from about a 100 km deep but they get carried up towards th
More Less

Related notes for EPSC 201

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.