The Sun-Earth-Moon System

1. The Sun-Earth-Moon System J. Dayton Earth Science Chapter 28

2. Tools of Astronomy (ways we learn about the universe) • Radiation • Telescopes • Satellites, probes, and space-based astronomy

3. What is Radiation? Light is also known as electromagnetic radiation which consists of electric and magnetic disturbances, traveling through space as waves. Includes: Visible light, infrared and ultraviolet radiation, radio waves, microwaves, X rays, and gamma rays.

4. Electromagnetic Radiation is classified by: Wavelengths Frequency This is the number of waves or oscillations occurring per second. For example, visible light has frequencies ranging from 4.3 x 1014 to 7.5 x 1014 Hz. • This is the distance between peaks on a wave. Looking back on the previous slide, the red length is longer than the purple length. • Another example is that radio waves have longer wavelengths than gamma rays.

5. Telescopes 4 Benefits: • Able to attach different detectors to telescopes to observe all wavelengths, especially those the human eye cannot detect. • A telescope brings much more light to a focus than the human eye can. • Telescopes allow astronomers to use specialized equipment. • Can be used to make time exposures with the aid of cameras or other imaging devices.

6. 2 types of telescopes used to focus “visible light” Refracting Telescope: Used a lens to bring visible light to focus. Reflecting Telescope: Brings visible light to focus with mirrors.

7. What is Interferometry? • The process of linking separate telescopes together so that they can act as one telescope. • This allows for tremendous detail.

8. Satellites, Probes, and Space-based Astronomy • Astronomers often have to send their instruments into space to collect the information they seek. • One reason for this is that Earth’s atmosphere blocks infrared and ultraviolet radiation, X rays, and gamma rays. • Another reason for sending instruments into space is to make close-up observations and even obtain samples from nearby objects in the solar system.

9. Have you ever heard of the Hubble Space Telescope (HST)?

10. Spacecraft In addition to making observations from above Earth’s atmosphere, space based exploration can be achieved by sending spacecraft directly to the bodies being observed. Probes are practical only for objects within our solar system because the stars are too far away!

11. Human Spaceflight The space shuttle allows scientists to study the effects of weightlessness on humans, plants, the growth of crystals, and other phenomena.

12. Spinoffs • Did you know that the technology for the space shuttles fuel pumps led to the development of pumps used in artificial hearts? • Did you know that the Apollo program led to the development of cordless tools? • In fact, more than 1,400 different NASA technologies have been passed on to commercial industries for common use, and are called SPINOFFS.

13. The Moon First satellite to launch to the moon was in 1957. It’s name was Sputnik I and was launched by the Soviet Union.

14. Yuri A. Gagarin • First human in space from Soviet Union in 1961.

15. Alan B. Shepard • The United States’ Project Mercury launched the first American on May 5, 1961.

16. Earth’s Moon • Unique • One of the largest • The orbit of the moon is unusual in that the moon is relatively farther from Earth than most moons are from the planets they orbit. • Solid, rocky body • Only large moon among the inner planets (Mercury and Venus have no moons at all and the moons of Mars are just two tiny chunks of rock.) • Made up of minerals similar to Earth, mostly silicates.

17. The Lunar Surface • Although the moon is the brightest object in the nighttime sky, the lunar surface is actually quite dark. • The Albedo of the moon is the amount of sunlight that its surface reflects. It is actually quite small.

18. Physical features of the Moon Highlands Maria Dark, smooth plains which are lower in elevation than the highlands. • Regions that are light in color, mountainous, and heavily covered with craters.

19. Physical Features Continued… Impact Craters Ejecta The material blasted out from an impact is the ejecta. • All of the craters on the moon are called impact craters. • These are formed when objects from space crash into the lunar surface.

20. Physical Features Continued… Rays Rilles Meandering, valleylike structures. • Long trails of ejecta are called rays that radiate outward. • These are visible on the moon as light colored streaks.

21. History of the Moon • The moon is very old: 3.8 to 4.6 billion years old. • The moon has a layered structure like Earth which consists of: crust, the upper mantle, the lower mantle, and the core. • Not tectonically active (No active volcanoes and no significant magnetic field)

22. How did our moon form? • Many theories have been proposed but only one is commonly accepted and that is the Impact Theory. • States that the moon formed as the result of a gigantic collision between Earth and a Mars-sized object about 4.5 billion years ago when the solar system was forming. • As a result of the collision, materials from the incoming body and from Earth’s outer layers were ejected into space, where they then merged together to form the Moon.

23. The Sun-Earth-Moon System

24. The Sun and Moon • Sun- Provides light and warmth and is the main source of energy that fuels our society. • Moon- Raises tides in our oceans and illuminates our sky with its monthly cycle of phases. • Every society from ancient times to the present has based its calendar and its timekeeping system on the motions of the Sun and Moon.

25. Because of Earth’s Rotation….. • The sun, moon, planets, and stars rise in the east and set in the west. • The sun, moon, planets, and stars do not orbit around Earth everyday. It only appears that way because we observe the sky from a planet that rotates once every day or 15

26. Because of Earth’s Rotation….. • The sun, moon, planets, and stars rise in the east and set in the west. • The sun, moon, planets, and stars do not orbit around Earth everyday. It only appears that way because we observe the sky from a planet that rotates once every day or 15º per hour.

27. How do we know the Earth is rotating? The Coriolis Effect: Flowing air and water on Earth are diverted from a north-south direction to an east-west direction as a result of the Earth’s rotation.

28. What is an Ecliptic? • The plane in which Earth orbits about the Sun.

29. Earth’s Tilt Earth’s axis is tilted relative to the ecliptic at 23.5º. Seasons are created by this tilt as the sun is oriented to the northern hemisphere for 6 months and oriented to the southern hemisphere the other 6 months.

30. Solstices Summer Solstice Winter Solstice The sun is directly overhead at the Tropic of Capricorn at 23.5º south latitude. Occurs around December 21st each year. The number of daylight hours in the southern hemisphere are at it’s max. • The sun is directly overhead at the Tropic of Cancer, which is at 23.5º north latitude. • This occurs around June 21st each year. • The number of daylight hours for the northern hemisphere are at their max.

32. Equinoxes “Equal Nights” Autumnal Equinox Vernal Equinox Same as Autumnal Equinox but on the opposite side of the ecliptic plane. • This is where the axis is not pointed at the Sun. • As a result, both hemispheres receive equal amounts of sunlight, and the Sun is directly overhead a the equator. • Thus, the lengths of day and night are equal for both the northern and southern hemispheres.

33. Phases of the Moon • The moon moves around the Earth! • The changes in the appearance of the Moon are called lunar phases. • We see the moon because of the sun’s reflection on the moon.

36. Motions of the Moon • The length of time it takes for the Moon to go through a complete cycle of phases, for example, from one full moon to the next, is called a lunar month. • The length of a lunar month is about 29.5 days.

37. Tides One of the Moon’s effects on Earth is the formation of tides. The Moon’s gravity pulls on Earth along an imaginary line connecting Earth and the Moon, and this creates bulges of ocean water on both the near and far sides of Earth. Earth’s rotation also contributes to tides. The ocean level rises and falls every 12 hours.

38. Tides Continued • Creates stronger tides on the ocean versus that of the Sun because it is closer to the Earth. • 2 Types of tides……

39. Tides Spring Tides Neap Tides When the moon is at a right angle to the Sun-Earth line, the result is lower than normal tides. • When the Sun and Moon align, the effects of the Sun and Moon combine and the tides are higher than normal.

40. Eclipses

41. Eclipses Continued… Solar Lunar Occurs when the Moon passes through Earth’s shadow. • Occurs when the Moon passes directly between the sun and Earth and blocks our view of the Sun.