Our Universe: Creation, Galaxies, Stars and Celestial Objects
Big Bang Theory Our universe began with one huge exploding atom that relapsed all the energy and matter that exists in the universe today. The Big Bang occurred 13.8 Billion years ago. Hydrogen and Helium, the makeup of stars, were the first two elements formed in less than a quarter of a second! The explosion was so enormous, that all objects in the universe are still moving outward today from the initial blast from billions of years ago! The radiation from this tremendous explosion is also still traveling across our universe in the form of microwaves (a specific type of energy that travels in forms of waves)
What is a Red Shift? Evidence to Big Bang Background Radiation Background radiation is the aftermath of gas, dust and energy from the initial explosion that is found in every part of our universe. It proves that there definitely was some explosion beyond enormous, billions of years ago! Red shift Red shift is a shift towards the red end of the spectrum of colors given off by objects in space. This RED shift demonstrates that object is moving away from us and everything else. The red shift is evidence of the push from the initial Big Bang. BLUE shift would demonstrate that an object is moving TOWARDS us!
W-MAP (Wilkinson Microwave Anisotropy Probe) Launched in January of 2001 Mapped the Cosmic Microwave Background (CMB) radiation (the oldest light in the universe) This radiation (and by extension, the early universe) is remarkably featureless; it has virtually the same temperature in all directions in the sky. W-MAP 14-106
Big Bang Timeline
Open Universe This theory states that everything in the universe will continue to move outward and away with continual expansion infinitely. Eventually, all stars would burn out leaving our universe with empty darkness. Future of the Universe Closed Universe This theory supports the idea that eventually that outward expansion from the initial Big Bang will wear. At this point, the force of gravity will begin to pull everything back together again. Then, another Big Bang will occur! Flat Universe A flat universe results if the expansion slows to a halt in an infinite amount of time but never contracts. Expansion occurs so slow that it appears to have stopped.
3 Types of Galaxies Galaxy- a cluster of billions and trillions of stars bound together by gravity Elliptical Galaxyround and flattened ovals (This is the most common type of galaxy) Irregular Galaxysmaller galaxies with no distinct shape. Spiral Galaxy- Galaxies with spiraling arms that rotate around a central bulge of massive substance in the center.
Our Galaxy: The Milky Way Our Milky Way is a spiral galaxy. The center of our galaxy is full of extremely massive, Red Super- Giant Stars. The center is over 28,000 light years away. Which means it takes 28,000 years for the light of the stars in the center to travel through space and be seen by our planet!!! The direction towards the center is toward the constellation Sagittarius 1 light year (which is measure of distance NOT time) is the distance light travels in a year. Light travels at a speed of 9.5x10 15 m/s!!! Our galaxy contains over 200 billion stars! Sun orbital speed around the center is 220km/s, orbital period is 240 million years. The sun will complete 20 revolutions around center in its lifetime. Sun It is believed that there may be a massive black hole at the center of our galaxy pulling the massive supergiants in!! The Size of Our Universe 1 light year = 5,865,696,000,000 miles!!!
Life Cycle of a Star White dwarf will eventually stop nuclear fusion and become a black dwarf- Dead Star Medium Star Gravity condenses the star to shrink (Where protostars are formed) Giant Star Star Size Comparison
Nebula- the birth of a star Orion Nebula Horsehead Nebula Lagoon Nebula A Nebula is a cloud of cosmic gas and dust where stars are formed. The gases of these nebulas are mostly hydrogen and helium. These are the two gases that make up all stars! Gravity begins to pull the gases inward during the birth of a star (accreation). Then, with gravity, the density of the gases increases which causes the pressure and temperature to increase, until the star finally stabilizes. A star can exist anywhere from 1 Million to 30 Billion years! (depending on size) Our Sun has around 5 Billion years remaining. It is predicted to only exist for 10 Billion total years.
Protostar: A baby star These are formed in the nebulas after the gases have condensed enough to begin nuclear fusion. Nuclear Fusion is the process that occurs in the cores of all stars. In Nuclear fusion, hydrogen atoms are converted into helium, releasing the ENORMOUS amount of energy that causes stars to become so very hot! The amount of energy released per gram of mass is equal to the amount of energy released by 22,000 tons of TNT. (The nuclear explosion at Hiroshima only released an amount equal to 13,000 tons of TNT) Young Stars Medium Star: Temperature= 6000 C Color = yellow/orange Example= Our Sun (closest star is proxima centauri) Size= over 90 million miles in diameter! (actually measured in solar radii)
Giant and Supergiant Stars Giant Stars Color= Red or orange Temperature= 4500 C Size= 10 x time the size of the Sun Red Super Giant Stars Color= Red Temperature= 3000 C Size= 1000 x the size of the Sun!! As size increases, the temperature decreases because the heat of nuclear fusion is spread out over such an enormous volume!
Supernova (large mass) or Planetary Nebula (small mass) If a star is extremely massive, the extreme density of the core collapses under the gravity causing a stellar explosion known as a supernova. The catastrophic explosion releases elements and cosmic dust for millions of the years. These explosions are more intense than 1 million nuclear bombs! Why are supernovae important to us? These explosions create the heavier elements that are used and make up humans!!! If a star has a lower mass, it will eventually shrink to a planetary nebula. The planetary nebula then condenses to a white dwarf and eventually a black dwarf. Computer Animation Actual Supernova- 70 mill light years away and occurred millions of years ago!
White and Black Dwarf Stars White Dwarf Stars: Color = White Temperature= 15,000 C Size= Average around the size of Texas Black Dwarf or Dead Stars These are stars that have burned out and nuclear fusion is no longer occurring, therefore these stars are creating no energy. Pressure causes these stars to become extremely dense, similar to squeezing an aircraft carrier into a glass jar! Both images are computer animations. Black Dwarfs do not give off any light to be seen.
Neutron Star Color: Blue Temperature: 35,000 C Size: A little larger than New York City (5-10 Miles) The Neutron Star is extremely dense and small. As the star decreases in size, the pressure increases so immensely that the temperature increases dramatically. As temperature increases, so does brightness. A Neutron Star is almost 1.5 million times brighter than our Sun! Density of a neutron star is 10 x 10 15 g/cm 3 10,000,000,000,000,000 g/cm 3
Black holes A black hole is a theoretical space where the gravitational pull is so incredibly strong that no radiation, including heat and light, can exist. These black holes are a million to a billion times more massive than our sun! Is there a black hole in the center of our Milky Way- YES! The fundamental descriptions of black holes are based on equations in the theory of general relativity developed by the German-born physicist Albert Einstein. The theory was published in 1916. The surface of a black hole is known as the event horizon. This is not a normal surface that you could see or touch. At the event horizon, the pull of gravity becomes infinitely strong. Thus, an object can exist there for only an instant as it plunges inward at the speed of light. These are computer animations- true black holes cannot be seen because light cannot reflect off them to create a shape. Galactic Blackholesweighing a few billion times the mass of the sun, most galaxies have a supermassive Blackholes in their center. (ours is slightly smaller than our solar system!) This is an actual black hole in the center of our galaxy. The black hole cannot be seen but we can see its gravitational pull eating everything around it
Hertzsprung-Russel Diagram
Variable Stars Variable Stars- stars that pulsate in brightness because of the expansion and contraction of their outer layers, or the blocking of their light by another object. Variable stars are brightest at their largest diameter and dimmest at their smallest diameter. DON T COPY: ONLY EXAMPLES RR Lyrae Variable Stars are stars that have periods of pulsation between 1.5 hours and 1 day, and on average, they have the same brightness. Cepheid Variable Stars have pulsation period between 1 and 100 days and the brightness (luminosity) doubles form dimmest to brightest.
Dark Matter and Dark Energy This is a force that is believed to be like an anti-gravitational force. Compared to water on the Earth, 78% of universe is dark matter!!! Dark matter and dark energy are still undefined today. We believe dark matter consists of subatomic particles, smaller than protons and neutrons! Scientists recognize the effects of dark energy, but they still do not know exactly what it is.
Celestial Objects: Asteroids, Meteors, Meteorites and Comets A. Asteroids- large pieces of rocky debris, some larger than our moon. A. Most asteroids in our solar system are located in the asteroid belt between Mars and Jupiter. B. Asteroids do not have a specific orbit, they cluster in the belt and are continuously knocked out or pulled in my Jupiter. B. Meteors and Meteorites: A. Meteors- pieces of rock that burn up in our atmosphere. (shooting star) B. Meteorite- pieces of rock that survive burning up in our atmosphere and land on the surface of the Earth. C. Comets- balls of ice and dust in a specific orbit in space. A. Kuiper Belt and Orrt Cloudsthese are two areas at the edge of our solar system where comets are located until knocked into a new, closer orbit. Computer animated asteroid impact Kuiper belt Meteor Shower Meteor Footage Images of asteroids in space Halley s Comet (Every 76 years) Meteorite
What if one hits us??? Asteroids and other objects come close to our planet EVERY DAY! Most of the time we never notice them, but with improving technologies we are detecting more of them, and detecting them earlier. In fact, on Wednesday Sept. 8 th, 2010 NASA telescopes spotted 2 asteroids (both around 30 feet in diameter) that came very close to Earth. One actually passed between the orbit of Earth and the Moon. Neither would have been large enough to cause large scale damage. The majority of these asteroids would burn up while entering our atmosphere.
-This blue ring is the Oort cloud, nearly a light year away (to put it in perspective) 1 2 -Sedna is the furthest known object to orbit our sun. The IAU (International Astronomy Union) has yet to define it as a planet/dwarf planet/asteroid. 4 3
Recent UARS satellite collision with Earth (Friday 9/23/11) -The UARS (Upper Atmosphere Research Satellite) was launched into orbit in 1991. -After years of observing the ozone, the 13,000 lb. chunk of metal has not been controllable by NASA since 2005. It has slowly been descending toward Earth. -Earth s gravity pulled the uncontrolled satellite back to earth. The debris fell to our surface, the largest chunk weighing 300 lbs. Animated UARS satellite orbit and crash
What about the one that killed the dinosaurs?