Our Universe : Creation, Galaxies, Stars and Celestial Objects

1. Our Universe: Creation, Galaxies, Stars and Celestial Objects

2. BIG BANG THEORY • universe began with one huge exploding atom that relapsed all the energy and matter that exists today • 13.8-15 Billion years ago • Hydrogen and Helium, the make-up of stars, were the first two elements formed in less than a quarter of a second!

3. explosion was so enormous, that all objects in the universe are still moving outward today from the initial blast! • radiation from this explosion is also still traveling across our universe in the form of microwaves (a specific type of energy)

4. Big Bang Timeline

5. Evidence of Big Bang • 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!

6. RED SHIFT • shift towards the red end of the spectrum of colors given off by objects in space • demonstrates that an object is moving away from us and everything else • is evidence of the “push” from the initial Big Bang • BLUEshift would demonstrate that an object is moving TOWARDS us!

7. Absorption Lines from a supercluster of galaxies

8. Common Questions about BIG BANG • Where is the center of the Universe? • There no center of the universe because there is no edge of the universe • In a finite universe, space is curved so that if you could travel billions of light years in a straight line you would finish back where you started. • It is also possible that our universe is infinite. In both examples, groups of galaxies completely fill the universe and are moving apart at all points making the universe expand

9. Where did the Big Bang occur in the Universe? • Space and time were created in the Big Bang. At the beginning of the universe, the space was completely filled with matter. • The matter was originally very hot and very dense and then expanded and cooled to eventually produce the stars and galaxies we see in the universe today.

10. Is the Earth expanding with the universe? • The Earth is not expanding and neither is the Milky Way galaxy. • These objects formed under the influence of gravity and stopped moving apart. • Gravity also holds galaxies together into groups and clusters. It is mainly the groups and clusters of galaxies that are moving apart in the universe.

11. What exists outside the universe? • Space was created in the Big Bang. Our universe has no edge or boundary - there is no outside of our universe.

12. What existed before the Big Bang? • Time was created in the Big Bang - we do not know if it existed before the Big Bang. • Some theories suggest that our universe is part of an infinity of universes (called a multiverse) which are being continuously created. This is possible but very hard to prove.

13. Future of the Universe

14. Open Universe • 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.

16. 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!

17. 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.

19. 3 Types of GalaxiesGalaxy- a cluster of billions and trillions of stars bound together by gravity

20. Elliptical Galaxy • round and flattened ovals • (This is the most common type of galaxy) • Messier 32 (2.65 millionlight-years away in the constellationAndromeda)

21. Irregular Galaxy • smaller galaxies with no distinct shape • Ex: Magellanic Clouds (160,000 light years away)

22. Spiral Galaxy • Galaxies with spiraling arms that rotate around a central bulge of massive substance in the center.

23. THE MILKY WAY • spiral galaxy • center is full of extremely massive, Red Super-Giant Stars • center is over 28,000 light years away

24. 1 light year (which is measure of distance, NOT time) is the distance light travels in a year. Light travels at a speed of 9.5x1015 m/s!!! • Which means it takes ________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 • Our galaxy contains over 200 billion stars!

25. STATISTICS AND FACTS • 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. • It is believed that there may be a massive black hole at the center of our galaxy pulling the massive supergiants in!! • Most stars in MW are 207,000 AU (AU= distance between sun and earth) apart, but in the center they are only 1000Au apart • AU = 149,597,871 km (92,955,807 miles)

26. 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

27. Nebula- the birth of a star • A Nebula is a cloud of cosmic gas and dust where stars are formed. • gases of these nebulas are mostly hydrogen and helium (the two gases that make up all stars!) • Gravity begins to pull the gases inward during the birth of a star. • Then, with gravity, the density of the gases increases which causes the pressure and temperature to increase, until the star finally stabilizes. Orion Nebula

28. Lagoon Nebula Horsehead Nebula

29. 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.

30. YOUNG STARS • Protostar: • A baby star - formed in the nebulas after the gases have condensed enough to begin nuclear fusion • In Nuclear fusion, hydrogen atoms are converted into helium, releasing the ENORMOUS amount of energy that causes stars to become 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)

32. Medium Stars • 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)

33. GIANT STARS • Color= Red or Blue • Temperature= 4500°C • Size= 10 x time the size of the Sun

34. RED SUPERGIANT STARS • Color= Red • Temperature= 3000°C • Size= 1000 x the size of the Sun!! • As size increases, temp. decreases because the heat of nuclear fusion is spread out over such an enormous volume!

35. SUPERNOVA (PLANETARY NEBULA) • 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! Actual Supernova- 70 mill light years away and occurred millions of years ago!

38. 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.

39. 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.

40. WHITE DWARF STARS • Color = White • Temperature= 15,000°C • Size= Average around the size of Texas

41. Neutron Star Color: Blue Temperature: 35,000°C Size: A little larger than New York City (5-10 Miles) 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!

42. Color of Stars • Stars are different colors depending on their distance, energy, age and temperature • Blue stars are the HOTTEST • Red stars are COOLER than blue stars

43. Brightness • The distance of a star affects its brightness • APPARENT Magnitude is how bright a star is depending on how far away it is from us on Earth • ABSOLUTE Magnitude is how bright a star is, assuming that ALL stars are the SAME distance away!

44. For Example: • The sun’s absolute magnitude is + 5, in comparison to other stars it’s not that bright • The sun’s apparent magnitude is -26.8 because to us, the sun is close and very bright

45. H-R Diagram • Hertz sprung-Russell diagram • Shows relationship between a star’s surface temperature and it’s absolute magnitude (actual brightness) • Usually a star will follow a diagonal line down the H-R diagram during it’s life time, this is called the MAIN SEQUENCE

47. BLACK HOLES • 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!

48. These are computer animations- true black holes cannot be seen because light cannot reflect off them to create a shape.

49. descriptions of black holes are based on equations in the theory of general relativity developed by Albert Einstein 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.

50. GALACTIC BLACKHOLES • weighing a few billion times the mass of the sun, most galaxies have a supermassive blackhole 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