Notes: The formation of the solar Sun, solar system and Earth Earth’s Beginnings Notes: The formation of the solar Sun, solar system and Earth

State Standards Earth and other planets in the solar system formed as heavier elements coalesced in their centers. Planetary differentiation is a process in which denser materials of a planet sink to the center, while less dense materials stay on the surface. A major period of planetary differentiation occurred approximately 4.6 billion years ago. In addition to the composition of Earth’s interior, the history of the formation of Earth and the relationship of energy transfer, transformation and convection currents within the mantle and crust are essential in understanding sources of energy.

The story of the Big Bang Long long ago, about 14 billion years to be exact, in a space that was a barely a few millimeters big, the Universe began… BANG!!! That’s what it probably sounded like as it expanded outward in all directions! But let us start before that explosion…  Before the Big Bang, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was more hot and denser than anything you can possibly imagine. Then, all of a sudden that hot, dense bubble exploded! The Universe that we know was born. Time, space and matter all began with the Big Bang. In a fraction of a second, the Universe grew from smaller than a single atom to bigger than a galaxy. And it kept on growing at a fantastic rate. In fact, it is still expanding today. As the Universe expanded and cooled, energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old. Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei. After 300,000 years, the Universe had cooled to about 3000 degrees. Atomic nuclei could finally capture electrons to form atoms. The Universe filled with clouds of hydrogen and helium gas. Those clouds would eventually condense into the billions of stars we see today.

Big Bang Theory (in a nut shell) The universe came into being at a single moment in an event called the Big Bang In every direction you look, galaxies at a given distance are moving away at the same rate Because astronomers know how fast the universe is expanding, they can infer how long it has been expanding The current estimate for the age of the universe is 13.7 billion years old

galaxies Huge groups of individual stars, star systems, star clusters, dust and gas bound together by gravity

Milky Way Galaxy – from earth

Milky Way Galaxy facts Contains 200 – 400 billion stars Over 100,000 light years across Average thickness is 10,000 light years, but its 30,000 light years in the center Every star you can see with the unaided eye is in the Milky Way galaxy The Sun is in one of the spiral arms about 2/3 of the way (or about 27,000 light years) from the center of the galaxy The sun orbits once around the Milky Way every 220 million years At the center of the Milky Way is a bulge of stars surrounded by star clusters Stars are forming out of dust in the spiral arms The next closest galaxy is Andromeda, 3 million light years away (THIS GALAXY IS MOVING TOWARDS THE MILKY WAY, THEY WILL EVENTUALLY COLLIDE!!! This event will occur in about 5 billion years…) What's REALLY at the center of the Milky Way?

Star Birth Stars form out of large clouds of gas and dust spread out over a large volume of space Our Sun and solar system form from a cloud of gas and dust known as the Solar Nebula Stars are born as a result of gravitational force Overtime, gravity pulls gas and dust together into a denser cloud known as a protostar Gravity continues to pull the cloud of gas and dust together until it is so hot and so dense that nuclear fusion (or the melding together of atomic nuclei) begins After fusion begins, the star has become an adult star, known as a main sequence star Our Sun is a main sequence star that is middle aged (about 5 billion years old)

NEBULA

PROTOSTAR

MAIN SEQUENCE STAR

Solar system formation The solar system began as a cloud of gas, ice, and dust called a nebula Gravity pulled all of these materials closer together, shrinking the nebula in to a flattened disk shape The disk began to rotate The materials in the center of the disk became denser and formed a star (the Sun). The planets began to take shape from the remaining bits of material The leftover material consisted of both gases and heavier elements Earth formed as gravity pulled particles together. As the particles collided they stuck together and formed large, unevenly-shaped objects. Gravity continued to pull more chucks of matter together until the Earth formed.

Solar System Formation

Why is the Earth Spherical? Eventually, Earth became massive and generated thermal energy in its interior Pressure and heat from radioactive decay of elements and the aftershocks of massive collisions caused the Earth to be molten The surface of the Earth eventually cooled and became the crust, but the outer core of the Earth is still molten Gravity pulled in the irregular bumps of the early Earth, resulting in a relatively smooth spherical surface

Planetary differentiation Differentiation is a scientific term which really means "to separate". A process in which denser materials of a planet sink to the center, while less dense materials stay on the surface Elements that make up plants separate in to different regions, but only if a planet is warm enough during its creation (the planet must be molten in order for separation to occur) This is similar to what happens when you put water and oil together (the oil floats on top of the water)

Earth’s Differentiation Different materials formed layers on earth according to their densities Remember: Density is the amount of mass in a material per unit volume Because the Earth was molten (or melted) denser materials could sink toward the middle of the Earth These materials (made of iron) formed the innermost layer of the Earth

Interior Structure of Earth The Earth has a circumference of about 24,901 miles at the equator Density (mass/volume), Temperature, and Pressure increase with depth in the Earth.

Earth’s Layers Outermost Layer = Crust Brittle, rocky, very thin, least dense Similar to the shell on a hard-boiled egg Directly below crust = Mantle Think middle layer in the solid part of Earth Denser than crust Below mantle = Outer Core Very dense, metallic center Liquid Center of Earth = Inner Core Dense ball of solid iron Under very high pressure

Understanding Earth’s layers The Earth has a layered structure. This layering can be viewed in two different ways: Layers of different chemical composition. Layers of differing physical properties.

Clues to earth’s Interior Deep mines and wells give hints about Earth’s interior The deepest mine ever constructed is a gold mine in South Africa (more than 4 km deep) The deepest well ever drilled is in Russia (more than 12 km deep)

Mponeng Mine Structure of Mine

Kola Peninsula Well in Russia

Temperature & Pressure Increase with Depth By digging mines and wells, scientists have discovered that it is HOT inside the Earth South African Gold Mines…127° F Kola Peninsula Well…374° F Pressure increases as depth increases inside Earth Due to the weight of the overlying rocks High temperature and pressure makes it hard to drill deep in to the Earth. The Kola Well is less than 1% of the distance to Earth’s center!

Indirect Methods of Studying Earth’s interior structure Scientists analyze Earthquake waves in order to figure out the structure of Earth’s interior Earthquakes release energy in the form of three types of waves These waves move through Earth traveling through all of Earth’s layers Different waves travel at different speeds through certain materials For example, some waves cannot travel through certain materials Some waves change direction when they hit a certain material Scientists use earthquake wave data to infer the density and composition of materials within Earth

Earth’s layers Activity Rock Density Activity Foldable Activity