Earth’s Place in the Universe

Cosmology Simply put, the study of the Universe (and everything in it… including us), its origin, present state, and its future can all be defined as Cosmology. Simply put, the study of the Universe (and everything in it… including us), its origin, present state, and its future can all be defined as Cosmology.

The Big Bang Most scientists believe in the theory that the Earth, our Solar System, our Galaxy, and the entire Universe began at one defining moment known as the Big Bang. Most scientists believe in the theory that the Earth, our Solar System, our Galaxy, and the entire Universe began at one defining moment known as the Big Bang. This doesn’t mean that this is the ONLY possibility, but it is the scientific theory that as the strongest evidence and the most support amongst the scientific community. This doesn’t mean that this is the ONLY possibility, but it is the scientific theory that as the strongest evidence and the most support amongst the scientific community.

Big Bang Continued… From this moment on, matter has been expanding outward for the last 13.7 billion years. From this moment on, matter has been expanding outward for the last 13.7 billion years.

The Big Bang Cont… As gravity began to condense small amounts of matter/gas together… As gravity began to condense small amounts of matter/gas together… –Galaxies formed and “clumped” together –Stars turned on –Planets formed

Cosmic Background Radiation Most of what we “think” we know about the beginning of the universe and the Big Bang came from the study of Cosmic Background Radiation. Most of what we “think” we know about the beginning of the universe and the Big Bang came from the study of Cosmic Background Radiation. –Discovered in 1965 –A persistent radio hiss (white noise) coming from all directions in space. –This tells us that radiation from the Big Bang has been cooling and moving outward in all directions

Galaxies In the universe, there are estimated to be between 50 billion and 100 billion galaxies In the universe, there are estimated to be between 50 billion and 100 billion galaxies Our sun is one of about 400 billion other stars in a spiral- shaped galaxy we call the Milky Way. Our sun is one of about 400 billion other stars in a spiral- shaped galaxy we call the Milky Way. We are located about half-way down one of the arms. We are located about half-way down one of the arms. Our galaxy is moving away from all other galaxies, except our nearest neighboring galaxy, Andromeda, which we are actually moving toward (gravity). Our galaxy is moving away from all other galaxies, except our nearest neighboring galaxy, Andromeda, which we are actually moving toward (gravity). Andromeda is about 2.5 million light years away. Andromeda is about 2.5 million light years away.

The Milky Way

Solar System About 5 billion years ago, our solar system formed when Hydrogen and Helium gas began to condense around a common center of gravity. About 5 billion years ago, our solar system formed when Hydrogen and Helium gas began to condense around a common center of gravity. When temperature and pressure became high enough, fusion began and the sun “turned on”. When temperature and pressure became high enough, fusion began and the sun “turned on”. The “shock wave” from this event blew lighter elements further out into the solar system. The “shock wave” from this event blew lighter elements further out into the solar system.

Solar System Continued… The strong pull of gravity from the sun pulled heavier elements like iron and nickel (metals) closer toward the center, forming the small, rocky inner planets that we call the Terrestrial planets. The strong pull of gravity from the sun pulled heavier elements like iron and nickel (metals) closer toward the center, forming the small, rocky inner planets that we call the Terrestrial planets. The lighter elements such as hydrogen and helium found their place a little further out, forming the larger outer planets that we call the Gas Giant/Jovian planets. The lighter elements such as hydrogen and helium found their place a little further out, forming the larger outer planets that we call the Gas Giant/Jovian planets. The left-over “stuff” formed asteroids, comets, meteors, dwarf planets, etc… The left-over “stuff” formed asteroids, comets, meteors, dwarf planets, etc…

The Solar System (distance not to scale)

Earth Around 4.6 billion years ago, at a distance of about 93 million miles, the Earth formed from the heavier elements floating around in space… such as iron, nickel, silicon and oxygen. Around 4.6 billion years ago, at a distance of about 93 million miles, the Earth formed from the heavier elements floating around in space… such as iron, nickel, silicon and oxygen. This material collected, forming a sphere about 8,000 miles in diameter. In the beginning, the Earth was a giant ball of… This material collected, forming a sphere about 8,000 miles in diameter. In the beginning, the Earth was a giant ball of… “liquid hot magma”. “liquid hot magma”.

The Core Heavier elements like Iron and Nickel compressed to form the core, while lighter elements like oxygen and silicon “floated” to the surface to create the rocky crust (rocks are largely composed of oxygen and silicon) Heavier elements like Iron and Nickel compressed to form the core, while lighter elements like oxygen and silicon “floated” to the surface to create the rocky crust (rocks are largely composed of oxygen and silicon) This Iron/Nickel core spins in the molten material beneath the surface, generating a magnetic field around the planet called the “Magnetosphere” This Iron/Nickel core spins in the molten material beneath the surface, generating a magnetic field around the planet called the “Magnetosphere”

Earth Continued… But space is cold and the Earth began to cool. As it cooled, the outer layer solidified and formed a thin shell of rock we call the surface (thinner than the shell of an egg, in respect). But space is cold and the Earth began to cool. As it cooled, the outer layer solidified and formed a thin shell of rock we call the surface (thinner than the shell of an egg, in respect). Inside, the magma was still really hot, and that heat began to escape through holes in the crust, creating volcanoes Inside, the magma was still really hot, and that heat began to escape through holes in the crust, creating volcanoes For million and millions of years, volcanoes spewed gas and water vapor into space. For million and millions of years, volcanoes spewed gas and water vapor into space.

Earth Continued… Earth’s gravity was strong enough to hold these gases close to the surface, eventually creating a blanket of gas surrounding our planet that we call the atmosphere. Earth’s gravity was strong enough to hold these gases close to the surface, eventually creating a blanket of gas surrounding our planet that we call the atmosphere. As more and more water vapor was added, clouds and weather began to form. Eventually enough rain fell to fill all of Earth’s low spots, creating our oceans. As more and more water vapor was added, clouds and weather began to form. Eventually enough rain fell to fill all of Earth’s low spots, creating our oceans. Comets may have also helped to add water to our oceans. Comets may have also helped to add water to our oceans. Without this blanket of gas, life on Earth COULD NOT EXIST. Without this blanket of gas, life on Earth COULD NOT EXIST.

Earth’s Internal Heat Source While the core of the planet has been cooling for billions of years, it is cooling slowly. While the core of the planet has been cooling for billions of years, it is cooling slowly. The decay of radioactive elements (and the heat that they produce) is the main source of internal heat/energy The decay of radioactive elements (and the heat that they produce) is the main source of internal heat/energy