Astronomy 101 Cumulative Presentation Aleks Alunans

Scale of Cosmos/Origin of Astronomy Earth was once thought to be the center of the universe Planets were thought to move in epicycles around Earth Ancient astronomers believed the Earth did not move because there was no parallax Nicolaus Copernicus set them straight, claiming the Earth revolved around the sun.

Telescopes Two main types include optical and radio telescopes Optical telescopes either reflect or refract Galileo pointed the first properly-built telescope at the heavens Telescopes rely on light-gathering power, resolving power, and magnifying power to reveal an image Light pollution diminishes the effectiveness of most Earth-based telescopes.

Atoms and Starlight Atoms contain protons and neutrons in the nucleus, with electrons orbiting around Isotopes have a different number of neutrons than protons Ions have lost or gained an electron, giving them a charge Atoms can combine to create molecules Atoms can move through space as radiation or energy, including starlight

Origin of the Solar System The Solar System is about 4.6 billion years old Apparently it all started as spinning gas, eventually condensing into the sun and other planets

Earth and Moon Earth is at least 4.3 billion years old The Moon is at least 4.48 billion years old Earth is covered in a thin solid crust with liquid magma and a metal core underneath Earth’s gravity is able to hold down an atmosphere The leading theory as to the origin of the moon suggest a large planetesimal collided with earth, knocking off a chuck that is now the moon

Terrestrial Planets The four stages of planetary evolution are differentiation, cratering, flooding, and slow surface evolution Terrestrial planets are made mostly of rock and metal There are four in our solar system: Mercury, Venus, Earth and Mars

Jovian Planets Jovian planets have no solid surface There are four in our solar system: Jupiter, Saturn, Uranus and Neptune The Jovian planets are farthest from the sun Their atmosphere’s consist primarily of hydrogen Clouds in the atmosphere form stripes and layers, often moving at different rates Gasses in these atmospheres condense into liquids, which are found at the core

The Sun and Stellar Properties The surface temperature of the sun is about 5800 degrees Kelvin The energy radiating from the sun is the result of nuclear fusion moving outward from the core Sunspots appear on the surface as cooler patches from the magnetic field The sun provides us with the energy needed to live. Plain and simple.

Stellar Evolution The life of a star begins with a giant cloud of dust and gas called a nebula This cloud condenses into a star and eventually begins radiating energy Stars live for billions of years, and depending on the mass can evolve into a small dwarf star or a super massive black hole

Comets and Asteroids Comets have a very long orbit around the sun The nucleus of a comet contains rock, ice, and other gasses that form a tail, always pointing away from the star it orbits Asteroids are mostly found in a belt between Mars and Jupiter They are thought to be the remains of planetesimals that were prevented from forming into planets by Jupiter’s gravity

The Milky Way The Milky Way is the galaxy in which our solar system is located It is estimated to be about 14 billion years old, about as old as the universe It is a barred-spiral galaxy, with the solar system located closer to the edge rather than the core There is a small stream of gas and dust that is visible and obscures the light from some stars, which is where the name Milky Way comes from

Galaxies A galaxy is a collection of millions of stars There are normal spiral, barred spiral, elliptical and irregular shapes of galaxies The nucleus is thought to contain a supermassive black hole, giving the galaxy its shape and apparent rotation Galaxies can be group in clusters Galaxies can collide to form even larger ones There are 100’s of millions of galaxies visible from earth

Cosmology Cosmology is the study of the universe The universe is constantly expanding, as shown by the red shift in the spectrum The universe is estimated to be about 15 billion years old, starting with a large explosion called the big bang There is debate as to whether or not the universe has a center or an edge We are a tiny, insignificant spec in comparison to the size of the known universe

Fate of the Universe The fate of the universe depends on the nature of dark energy The universe may continue expanding forever, distancing galaxies and stars from each other indefinitely The universe may eventually tear, pulling atoms apart one by one