What is Astronomy?

1. Welcome to Earth Science! Unit 6 What is Astronomy?

2. Astrology • The study of celestial objects, spaceand the universe. EX. moons, planets, stars, nebulae, and galaxies. Includes the physics, chemistry, mathematics, and evolution of these objects, and phenomena that originate outside the atmosphere of Earth. • Ex. supernovae explosions, gamma ray bursts, and cosmic background radiation.

3. What is a Theory? Once a hypothesis has been tested multiple timesand generally accepted, it may lead to the development of a theory. A theory is a hypothesis or a set of hypothesis that is supported by the results of significant experimentation and observation.

4. Light and the Doppler Effect • In 1665, Isaac Newton observed that sunlight passing through a glass prism produced a rainbow of colors: red, orange, yellow, green, blue, and violet. • Newton named this display of colors the spectrum.

5. Light and the Doppler Effect • He determined that light travels in waves.

6. Light and the Doppler Effect • The distance from the crest of one wave to the next is a wavelength. • Each color in the spectrum has a different wavelength. • Red has the longest wavelength • Violet has the shortest wavelength.

7. Light and the Doppler Effect When a light source is moving toward an observer, the wavelengths of the light produced are shorter When a light source is moving away from an observer, the light waves produced are longer.

8. Doppler Effect Higher Frequency Lower Frequency

9. Doppler Effect

10. Light and the Doppler Effect The shift in the wavelengths of energy emitted by an energy source moving away from or toward an observer is called the Doppler Effect.

11. Light and the Doppler Effect • Scientists have been making observations for hundreds of years. • They continue to observe movement of red shaded galaxies. This is known as the “ Red Shift”

12. What does that mean? Check it! • Which way is the galaxy moving? • Put up a fist if you think the galaxy is moving away from Earth. • Put up a five if you think the galaxy is moving toward Earth.

13. Big Bang Theory • The “Red Shift” is the biggest evidence for the Big Bang Theory. • The Big Bang Theory establishes that the universe is expanding (which can be seen through the red tint of galaxies).

14. The Big Bang Theory • As the cloud expanded, some matter clumped together to form galaxies • The universe is continuously expanding and moving apart from one another • This theory also hypothesizes when time began: period of extreme and rapidexpansion about13.7 billion years ago.

15. Big Bang Theory LT#3/14 Evidence: • This theory is supported by the fact that it provides explanation for observations of distant galaxies receding from our own; of the measured composition of stars, earthly gases, and residual radiation that still fills the universe. • Scientists use information from amounts of radiation AKA radiometric dating to calculate the age of meteorites, moon rocks, and Earth’s oldest minerals.

16. Big Bang and Nucleosynthesis • The Universe's light-element abundance is another important criterion by which the Big Bang hypothesis is verified. • The cosmic formation of elements more complex than the hydrogen. • Light elements (namely deuterium, helium, and lithium) were produced in the first few minutes of the Big Bang. • Heavier elements originate in the interiors of stars which formed much later in the history of the Universe.

17. Nucleosynthesis • Taken place between approximately 10 seconds until 20 minutes after the Big Bang, and is calculated to be responsible for the formation of most of the universe's helium.

18. Big Bang Theory

19. Evolution of the Universe Cosmic Evolution Formation of Milky Way Formation of Earth Origin of Matter Present Big Bang

20. What is a star? LT#4 • A star is a body of gases that gives off a tremendous amount of radiant energy in the form of light and heat. • All life on Earth is dependent on the Sun, the star closest to the Earth. This is because the sun provides a critical forms of energy: light and heat

21. Importance of Stars • This is important to life on Earth because: • Plants need light to perform photosynthesis and make energy. • We need a certain temperature for life to occur (Venus & Mars=no life) • Why?

22. Development of a Star • Stars go through a sequence of developmental stages: • They are formed; evolve in size, mass, and brightness; and eventually burn out. • Astronomers classify stars according to their color (spectral type), composition (elements), and temperature.

23. How to Classify a Star

24. Life Cycle of a Star

25. Structure of the Sun • The Sun is a medium-sized star about halfway through its predicted life span of about 10 billion years. • What will happen when the Sun burns out? • Life on Earth will end? • Sun will explode, supernova, and left over material will form a new star and planetary systems. • The sun has three basic regions: • The core • The inner zones • The atmosphere

27. The Core • The core is the center of the sun • Makes up 10% of the sun’s diameter • The temperature of the core is about 15,000,000 degrees Celsius • No liquid or solid can exist at that temperature, so it is purely gas

28. The Core LT# 5 • The sun’s mass is 300,000 times the earth’s mass. • Therefore the force of gravity is much greater and the center is very dense. • There is constant nuclear fusion happening within the sun’s core.

29. Nuclear Fusion = Energy! • Nuclear fusion produces energy in the sun’s core that will reach Earth and be used to sustain life on Earth. • Does three things: • Converts hydrogen into helium (or rather, makes helium nuclei from protons) • Converts mass to energy. Fusion of hydrogen helium • This energy causes the sun to shine

30. Who discovered that mass changes to energy? LT#8 • Albert Einstein • Theory of relativity • A lot of energy can come from little mass • E = mc2 • Tells us that the energy (E) generated equals the mass lost (m) times the speed of light squared (c2). • Approximately half of a billion tons of hydrogen is being converted into helium each second. That’s a lot of ENERGY!!!

31. Fusion LT#5 • Video: http://www.youtube.com/watch?v=pusKlK1L5To • The reactions produce high-energy photons (gamma rays) that move through the "radiative layer" surrounding the core. • Nuclear fusion within stars produces all elements lighterthan and including iron, and the process releases the energy seen as starlight. • Heavier elements are produced when certain massive stars achieve a supernova stage and explode.

33. Sunspots • The cooler areas of the sun will appear darker than the areas surrounding them • Cool, dark areas of gas within the photosphere that are caused by powerful magnetic fields are called sunspots

35. Sunspot Cycle • Sunspots initially appear in groups about midway between the sun’s equator and poles • As they slowly disappear, new ones appear near the suns equator • The cycle is usually about 11 years long

36. Prominences • The magnetic fields that cause sunspots also create other disturbances • One of these disturbances are great clouds of glowing gases, called prominences • These form huge arches that reach high above the sun’s surface • These can arch over 300,000 miles above the surface • These can last for several weeks, while others can exist for up to a year

38. Solar Flares • One of the most violentof all solar disturbances would be a solar flare • A solar flare is a sudden outward eruption of electrically charged atomic particles • They can extend up to several thousand miles within minutes • They are usually less than an hour in length • They occur near sunspots, and at a peak in the sunspot cycle, can have between 5 and 10a day

40. Magnetic Storms • Some particles from a solar flare are flung out with so much force that they escape into space • As the gusts of solar-wind particles enter the atmosphere of the earth, they can disturb the Earth’s magneticfield • This disturbance is called a magnetic storm • These can interfere with radio communications on Earth • The average occurrence is less than one per year

41. Auroras • Bands of light seen in the sky from earth due to magnetic storms • The electrically charged particles of the solar wind strike the gas particles in the upper atmosphere, producing green, red, blue or violet sheets of light • These are also callednorthernlights or southern lights • More commonly seen in the polar regions of the earth and sometimes at the equator

43. The Planets LT#7

44. Mercury • Mercury is the planet closest to the sun • Therefore, Mercury has a shorter orbit period than any other planet- 88 days • It rotates very slowly on its axis – once every 59 days • It is so close to the sun that light from the sun usually obscures the planet from view • Mercury has no moons

45. Venus • The second planet from the sun is Venus • The orbit of Venus is 225 days, although it also rotates very slowly-once every 243 days • The direction of rotation is opposite that of the other planets • This is the only planet in which the sun rises in the west and sets in the east • Venus also has nomoons

46. Earth • The third planet from the sun is Earth • The orbit period for Earth is 365.24 days, completing one rotation in 23 hours and 56 minutes • Earth is the 5thlargest planet • Earth has one moon

47. Earth: Where Life Exists! • Life is able to exist on Earth because of the distance from the sun • The temperature is warm enough for water to exist as a liquid • Mercury and Venus are too close to the sun, therefore water evaporates • Mars and the other planets are so far that most of the water is in the form of ice

48. Mars • Mars is the fourth planet from the sun • Its orbit period is 687 days and its rate of ration is 24 hours, 37 minutes • The length of day on Mars and Earth are almost the same • Mars also has seasons like Earth because of the tilt of its axis • Mars has two moons

49. Jupiter • The first of the outer planets, 5th from the sun • The largest planet in the solar system • Its mass is two times that of the other eight planets combined • Its orbit around the Sun is 12years • Jupiter rotates faster than any other planet – every 9 hours and 50 minutes • Jupiter has 17moons and 4rings

50. Saturn • The 6th planet from the sun • Saturn is about half a billionmiles fartherfrom the sun than Jupiter • The secondlargest planet • The average temperature is -284 degrees • Saturn has 18 moons and several rings