Downloaded 23 times
More Related Content
![Solar system formation[1]](https://cdn.slidesharecdn.com/ss_thumbnails/solarsystemformation1-101108181240-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
Astronomy
- 1.
- 2. Where are wein the universe?
- 3. We live onEarth, the third planet of our solar system.
- 4. Our solar systemis located in the Milky Way Galaxy, a collection of 200 billion stars (together with their solar systems).
- 6.
- 7. Spiral galaxies are galaxies with a central, dense area and spiraling arms (which are often sites of star formation).
- 8. There are twotypes of spiral galaxies, "S" (normal spiral) and the less common "SB" (barred spiral, with an elongated center).
- 9.
- 11. Barred Spiral, withan elongated center
- 13.
- 14. Our solar systemconsists of the sun, planets, dwarf planets (or plutoids), moons, an asteroid belt, comets, meteors, and other objects. The sun is the center of our solar system; the planets, over 61 moons, the asteroids, comets, meteoroids and other rocks and gas all orbit the Sun.
- 16.
- 17. The nine planetsthat orbit the sun are (in order from the Sun): Mercury, Venus, Earth, Mars, Jupiter (the biggest planet in our Solar System), Saturn (with large, orbiting rings), Uranus, Neptune, and Pluto (a dwarf planet or plutoid).
- 19. A belt ofasteroids (minor planets made of rock and metal) orbits between Mars and Jupiter. These objects all orbit the sun in roughly circular orbits that lie in the same plane, the ecliptic (Pluto is an exception; this dwarf planet has an elliptical orbit tilted over 17° from the ecliptic).
- 21. The inner planets(those planets that orbit close to the Sun) are quite different from the outer planets (those planets that orbit far from the Sun).
- 22. The inner planetsare: Mercury, Venus, Earth, and Mars. They are relatively small, composed mostly of rock, and have few or no moons.
- 23. The outer planetsinclude: Jupiter, Saturn, Uranus, and Neptune. They are mostly huge, mostly gaseous, ringed, and have many moons (plus Pluto, which is a dwarf planet that has one large moon and two small moons).
- 24.
- 25. There are othersmaller object that orbit the Sun, including asteroids, comets, meteoroids and dwarf planets.
- 26. Asteroids (also calledminor planets) are rocky or metallic objects, most of which orbit the Sun in the asteroid belt between Mars and Jupiter.
- 28. Comets are small,icy bodies that orbit the sun. They have very long tails.
- 30. Meteoroids are smallbodies that travel through space. They are stony and/or metallic and are smaller than asteroids. Most are very tiny.
- 32.
- 33. Our sun isa star located at the center of our Solar System. It is a huge, spinning ball of hot gas and nuclear reactions that lights up the Earth and provides us with heat
- 34. HOW FAR AWAYIS THE SUN?
- 35. Our sun isa medium-sized yellow star that is 93,026,724 miles (149,680,000 km or 1 Astronomical Unit) from the Earth.
- 36. THE TEMPERATURE OFTHE SUN
- 37. The Sun's corecan reach 10 to 22.5 million°F. The surface temperature is approximately 9,900°F (5,500°C). The outer atmosphere of the Sun (which we can see during a solar eclipse) gets extremely hot again, up to 1.5 to 2 million degrees. At the center of big sunspots the temperature can be as low as 7300 °F (4300 K, 4000 °C). The temperature of the Sun is determined by measuring how much energy (both heat and light) it emits.
- 39. AGE OF THESUN
- 40. The Sun formed4.5 billion years ago, as the solar system coalesced from a cloud of gas and dust.
- 41.
- 42. Astronomers study theSun using special instruments. Scientists analyze how and why the amount of light from the Sun varies over time, the effect of the Sun's light on the Earth's climate, spectral lines, the Sun's magnetic field, the solar wind, and many other solar phenomena. The outer regions of the Sun (the corona) are studied during solar eclipses.
- 45.
- 46. Each star inthe sky is an enormous glowing ball of gas. Our sun is a medium-sized star.
- 47. Stars can livefor billions of years.
- 48. A star isborn when an enormous cloud of hydrogen gas collapses until it is hot enough to burn nuclear fuel (producing tremendous amounts heat and radiation). As the nuclear fuel runs out (in about 5 billion years), the star expands and the core contracts, becoming a giant star which eventually explodes and turns into a dim, cool object (a black dwarf, neutron star, or black hole, depending on its initial mass). The largest stars have the shortest life span (still billions of years); more massive stars burn hotter and faster than their smaller counterparts (like the Sun).
- 49. There are largergroups of stars, called clusters.
- 50. WHY ARE STARSHOT AND BRIGHT?
- 51. Nuclear Fusion and Nucleosynthesis
- 52. Stars are giantnuclear reactors. In the center of stars, atoms are taken apart by tremendous atomic collisions that alter the atomic structure and release an enormous amount of energy. This makes stars hot and bright. In most stars, the primary reaction converts hydrogen atoms into helium atoms, releasing an enormous amount of energy. This reaction is called nuclear fusion because it fused the nuclei (center) of atoms together, forming a new nucleus. The process of forming a new nucleus (and element) is nucleosynthesis.
- 53. WHAT IS THECLOSEST STAR?
- 54. The closest starto us is the sun! Other than that, the closest star is Proxima Centauri, aka Alpha Centauri C (the dimmest star in the Alpha Centauri system). Proxima Centauri is 4.3 light- years from the Sun. It has an absolute magnitude of 15.5.
- 55. WHY DO STARSTWINKLE?
- 56. The scientific namefor the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.
- 58.
- 59. That's easy. Astronomy is the study of Outer Space.
- 60. Why should westudy Outer Space?
- 61. We study OuterSpace because we are part of it. That's right. You are part of outer space, everything is.
- 62.