Basic Astronomy

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Information about Basic Astronomy

Published on December 13, 2016

Author: earshadshinichi

Source: slideshare.net

1. Astronomy Astronomy is the scientific study of stars, planets and other things in space.

2. Origins of the Universe 1. Creationism – universe is created by a deity or spirit, anchored on holy books 2. Big Bang Theory – primordial explosion that created the universe (primordial atom) 3. Steady State Theory – the universe has always been as it is today

3. Planetary Nebula or Close Encounter? Historically, two hypothesis were put forward to explain the formation of the solar system…. 1. Gravitational Collapse of Planetary Nebula (Latin for “cloud”) Solar system formed form gravitational collapse of an interstellar cloud or gas 2. Close Encounter (of the Sun with another star) Planets are formed from debris pulled out of the Sun during a close encounter with another star. But, it cannot account for • Probability for such encounter is small in our neighborhood…

4. The Nebular Theory* of Solar System Formation Interstellar Cloud (Nebula) Protoplanetary DiskProtosun Gravitational Collapse Terrestrial Planets Accretion Nebular Capture Jovian PlanetsAsteroids Leftover Materials Comets Leftover Materials Metal, Rocks Condensation (gas to solid) Sun Gases, Ice Heating  Fusion *It is also called the ‘Protoplanet Theory’.

5. A Pictorial History Gravitational Collapse Accretion Nebular Capture Interplanetary Cloud Condensation

6. The Interstellar Clouds • The primordial gas after the Big Bang has very low heavy metal content • The interstellar clouds that the solar system was built from gas that has gone through several star-gas-star cycles.

7. Solar System

8. What’s in Our Solar System? • Our Solar System consists of a central star (the Sun), the nine planets orbiting the sun, moons, asteroids, comets, meteors, interplanetary gas, dust, and all the “space” in between them. • The nine planets of the Solar System are named after Roman Gods and Goddesses.

9. Models of the Solar System 1. Geocentric model - earth is the center; proposed by Ptolemy

10. Models of the Solar System 2. Heliocentric model - sun is the center; proposed by Copernicus

11. The Relative Size of the Planets in the Solar System

12. Solar System Sun – yellow star; driven by thermonuclear fusion, by which hydrogen nuclei fuse to form helium i. Photosphere – surface ii. Sunspots – cooler and darker portion on the Sun’s surface iii. Chromosphere – sphere of color, seen during eclipse iv. Corona – outermost region

13. Chromosphere Prominences Sun Spots

14. The Sun actually moves! Rotation: The Sun spins around one time every 25 days. Revolution: The Sun moves around the center of our galaxy one time every 200,000,000 years!

15. Our Differing Distances from the Sun A.Aphelion – when the Earth is far away from the sun, about 152 million km away B.Perihelion – when the Earth is closest to the sun, about 147 million km away

16. Equinox & Solstice Equinox is when daylight time is equal to night time. Solstice is when daytime or night time is longer than the other; may be winter, when night time is longer, or summer when daytime is longer.

17. General Characteristics of Major Planets - Dynamical • Nearly circular orbits (Mercury and Mars most eccentric) • All orbit within 10o of Earth’s orbital plane

18. General Characteristics of Major Planets •All revolve in the same direction • All rotate in the same direction (except Venus)

19. Solar System Planets 1. Inner planets (terrestrial planets) - composed primarily of rock and metal; have relatively high densities; slow rotation; solid surfaces; no rings 2. Jovian planets (gas planets) - composed primarily of hydrogen and helium; have low densities; rapid rotation; deep atmospheres; rings

20. Mercury • Mercury has a revolution period of 88 days. Mercury has extreme temperature fluctuations, ranging from 800F (daytime) to -270F (nighttime). • Even though it is the closest planet to the sun, Scientists believe there is ICE on Mercury! The ice is protected from the sun’s heat by crater shadows. • Messenger of gods

21. Venus • Venus is the brightest object in the sky after the sun and moon because its atmosphere reflects sunlight so well. People often mistake it for a star. • Its maximum surface temperature may reach 400C. • Venus has no moons • Greenhouse Model • “The Morning Star” • Goddess of Beauty

22. Earth • Earth is the only planet known to support living organisms. • Earth’s surface is composed of 71% water. – Water is necessary for life on Earth. – The oceans help maintain Earth’s stable temperatures. • Earth has one moon and an oxygen rich atmosphere.

23. Motion of the Earth Rotation Revolution

24. The Moon The Moon is the Earth’s only natural satellite. Ancient man feared the moon - thought it made a person crazy! 1609, Galileo was the 1st person to fully examine the moon through a telescope. The moon is about a ¼ of the size of Earth. Rotation: 27 1/3 days Revolution: 27 1/3 days

25. The Moon Great Impact Theory – moon is the result of the collision of a huge rocky mass the size of planet Mars with the Earth about 20 million years after the Earth had formed; the collision formed a ring of clouds and rock fragments from both bodies around the Earth until by gravity it formed the Moon

26. This shows the craters and the smooth areas on the moon.

27. Q: 1. Can a full Moon be seen at noon? 2. Can a new Moon be seen at midnight? A: Both, no. You would be on the wrong side of Earth to view the full moon and the new moon.

28. Eclipse: Solar • Moon’s shadow fall on the earth • During new moon

29. Eclipse: Lunar • Earth’s shadow fall on the earth • During full moon

30. • Like Earth, Mars has ice caps at its poles. • Mars has the largest volcano in our solar system: Olympus Mons. • Mars appears red because of iron oxide, or rust, in its soil and an atmosphere of CO2 • Mars has two moons (Phobos & Deimos) and takes about two years to complete an orbit. • Probes: Curiosity, Opportunity, Spirit Mars

31. Jupiter • Jupiter is the largest and most massive planet. • Diameter is 11 times bigger than that of the Earth’s. • Takes about 12 years for Jupiter to orbit the sun. • Jupiter has 16 well-known moons. Four famous moons: Ganymede, Calisto, Io, & Europa • “Great Red Spot”

32. Saturn • Saturn is composed almost entirely of hydrogen and helium • Saturn has many rings made of ice and rocks. Saturn’s rings are very wide. • It takes Saturn about 30 years to orbit the sun. • Saturn has 62 known moons (Titan & Enceladus, being the largest) composed largely of ice, some of which orbit inside the rings! • Named after the Roman god of agriculture

33. Uranus • Uranus is blue in color due to methane gas in its atmosphere. • Uranus has 11 dark rings surrounding it. • Uranus has 27 known moons (Titania, Oberon, Umbriel, Ariel, & Miranda) and takes 84 years to complete one orbit. • Tilted by over 90 degrees • Named after the Roman god of the sky

34. Neptune • Neptune has the fastest winds in the solar system: up to 2,000 km/hr. • Neptune is also blue in color due to methane gas in its atmosphere. • takes 165 years to orbit the sun and has 14 moons, Triton is one of the known moons • “Great Dark Spot” • The god of the sea

35. Pluto • Pluto has only one moon and takes about 249 years to orbit the sun. • Part of Pluto’s orbit passes inside that of Neptune, so at times Neptune is the planet farthest from the sun. • Pluto was located and named in 1930, but today Pluto is no longer considered a planet. • New Horizon fly-by

36. Dwarf Planet/ Kuiper Belt Object/ Dwarf Planet Pluto – 1930-2006 classified as major planet; its famous moon is named Charon Reasons why it is not one of the major planets: 1. Most often located in Kuiper Belt Region 2. Orbit is highly elliptical & steeply inclined to the planetary plane 3. Composition does not match any of the other planets, but is a near-perfect match to objects in Kuiper Belt

37. Quantitative Planetary Facts

38. Comets • Comets are small bodies typically only a few kilometers across, composed largely of volatile ices. • Have highly eccentric orbits • Known to have a coma and a “tail” – Perseids (July 23- Aug 20) – Orionids (Oct 16-27)

39. The Milky Way Galaxy The Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye.

40. Our galaxy is called the Milky Way Our WHOLE solar system is located right about here X

41. Galaxies – group of star and solar systems Galaxies vary in shape: • Spiral • Andromeda Galaxy • Ring • Hoag’s Object • Irregular

42. Stars go through four different stages in their lifetime. The four stages are: 1.Yellow Star 2.Red Giant 3.White Dwarf 4.Black Dwarf

43. • Medium-Hot star. Nuclear reaction occurring • Our “Star” (sun) is a yellow star.

44. •As nuclear fuel is used up, star expands and turns red •Lasts for about 100 million years •When our sun is a Red Giant, it will expand and swallow up the inner planets—Mercury, Venus, Earth & Mars

45. •Most of the stars fuel in the outer layers is used up •Shrinks and collapses (about the size of Earth but heavier) •Gives off a white light

46. •Remaining fuel is used up •Star is dead

47. The universe is made up of millions of Galaxies. A galaxy is a swarm of billions of stars, clouds and dust rotating around a central point.

48. Stars & Constellations • Constellations are group of stars. Zodiac is based from these constellations. • Nearest Star from the Sun is the Proxima Centauri • Brightest Star is Sirius of Canis Major • Most common constellation and star are the “Ursa Minor” and the Northern Star “Polaris” of the Ursa Minor, respectively. • Largest known star is the VY Canis Majoris

49. Supernova & Black hole Supernova is a large explosion that takes place at the end of a star's life cycle. Black hole is a region of space-time exhibiting such strong gravitational effects that nothing can escape from inside it.

50. Lunar Missions •Lyka was the first animal sent in the space, to orbit the Earth. •The first successful manned mission to the moon. (Apollo 11) •Astronauts Neil Armstrong and Buzz Aldrin were the first men on the moon, (July 16, 1969, 8:18 PM) •Astronauts = NASA, Americans •Cosmonauts = USSR, Soviets

51. Due to the extreme conditions on the moon astronauts must were a suit like this.

52. This shows the surface of the moon Little Astronaut

53. And away we go!

54. The Astronomical Units Often planets’ distance from the Sun is measured by ASTRONOMICAL UNITS. This is the relative distance of the Earth from the Sun. SO when we say 2 Astronomical Units, it means twice the distance of Earth from the Sun.

55. Light-year The distance that light travels in one year, about 9.5 trillion kilometers. Parsec: A unit of measurement used to describe distances between celestial objects, equal to 3.258 light-years. Important Astronomical Measurements

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