Moons and Other Solar System Objects

Moons and Other Solar System Objects
Chapter 17 Moons and Other Solar System Objects Sections

The Moon July 20, 1969 – humans first landed on moon
What was the first word transmitted from the surface of the moon? “Houston . . . Retroreflector – placed on moon and designed to reflect a laser beam from earth Rates of Continental Drift on earth, change in earth’s tilt, distance to moon, Gravitational Constant (G) Average distance = 384,000 km (240,000 mi) Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

The Moon Second brightest object in the sky
“moon” – unknown origin of the word Many primitive and modern societies base their religious ceremonies on the cycles of the moon (e.g., new and full moons). Our month is based on moon’s cycle. Human ovarian cycle is also synchronized to the 29.5 day lunar cycle. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Composition and History of the Moon
Since the first manned lunar landing on July 20, 1969, there have been 5 other lunar landings – Apollo 12, 14, 15, 16, & 17. 379 kg (over 800 lbs) of lunar material have been brought back to earth. Using radiometric dating techniques Mountain rocks – 4.4 to 3.9 billion years old Plain rocks – 3.9 to 3.1 billion years old No rocks older than 4.4 or younger than 3.2 billion years old have been found. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

General Features of the Moon
Largest moon of any of the terrestrial planets (Mercury, Venus, Earth, and Mars) One complete revolution = 29.5 days (approx.) The moon rotates on its axis at the same rate, and therefore we only see one side of the moon. Since the moon rotates every 29.5 days, the sun would appear to rise/set every 29.5 days. The surface features of the moon formed millions of years ago without erosion to erase them. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Characteristics of the Moon
Nearly spherical, with a diameter of 3476 km (2160 mi) – approx. ¼ the earth’s diameter Mass of the moon = 1/81 of the earth Average density of 3.3 g/cm3 (earth is 5.5) Surface gravity of the moon is only one-sixth of Earth’s. Therefore one’s weight on the moon would only be one-sixth of that on Earth. Average reflectance (albedo) = only 7% (only 7% of the light received from the sun is reflected) Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Composition of the Moon
Core, mantle, crust All thought to be solid Crust, thicker on one side Presently does not have a magnetic field Interestingly though, the rocks brought back show some magnetism, indicating that the moon had a slight magnetic field at the time of rock crystallization. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Prominent Features of the Moon
Other than the very obvious phases of the moon, the moon’s most prominent features include craters, basins, plains, rays, rills, mountains, and faults. Crater – Greek for “bowl-shaped” Lunar craters are large to small and believed to have been formed by meteorite impacts. For individual craters, the volume of the rim and the crater are about equal. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Craters and Basins Craters are the best known features of the moon’s surface. About 30,000 can be seen using an earth-based telescope. Range in size – microscopic to 100’s km The shapes of the craters change with diameter. 1 km – smooth bowl-shaped interiors >1 km – flat interiors >>1 km – flat floor with central peak Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Craters of the Moon Most of the craters were formed between 4.4 and 3.9 billion year ago, due to a time of intense meteorite bombardment. After 3.1 billion years ago, the moon cooled down enough that molten rock could no longer get to the surface. The moon appears to have been geologically quiet for the past 3.1 billion years or so. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Lunar Plains Also call maria (Latin for ‘seas’)
Lunar plains - large, dark, flat areas on the moon believed to be craters formed by meteorite impact that then filled with volcanic lava Dark in appearance because these flat plain areas reflect even less light than the average surface area of the moon Surface of the moon covered by a layer of loose debris called regolith Rock samples examined - similar to volcanic rock on earth Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Plains of the Moon Plains were produced by volcanic eruptions and the resulting enormous lava flows. Apparently the moon’s interior was hot enough to cause these major eruptions from billion years ago Plains are more common on the near side of the moon, probably due to the thinner crust (where it is easier for the molten material to reach the surface). Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Rays Rays - streaks that extend outward from some of the craters
Thought to be pulverized rock that was thrown out when the crater formed These rays are brighter (reflect more light) than the crater – (powdered rock reflects more light than regular-sized rock) Occasionally the ray systems are also marked by secondary craters formed by flying debris thrown from the primary crater. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Rills Rills - long, narrow trenches or valleys
Some are straight and some are curved. Thought to represent a separation (or crack) caused by moonquakes Similar features are known to form because of earthquakes. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Mountain Ranges Mountain ranges on the moon can be as high as 6100 m (>19,000 ft) All mountain ranges appear to be formed in a circular pattern, bordering the lunar plains. Therefore, they were probably not formed by the same processes as mountain ranges on earth. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Faults Fault - a break or fracture in the surface of the moon, along which movement has occurred Results from the movement of the moon’s crust along a break Since there is little/no erosion on the surface of the moon, the difference in elevation caused by these faults remain for millions of years. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Origin of the Moon?? Must take into account these facts:
Lunar rocks are similar to the earth’s mantle. Oxygen isotope ratios indicate that the earth and the moon were formed at a similar distance from the sun. There is no water in lunar rocks. There is a deficiency of volatile elements (which were driven off by heat). Relative to earth, moon has less iron. 3.3 g/cm3 = moon; g/cm3 = earth The oldest rocks on earth and moon are similar. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Origin of the Moon Most widely accepted theory is the great impact theory. A planet-sized object (size of Mars) struck the earth with a glancing blow 4.4 billion years ago, resulting in the ejection of matter into orbit to form the moon. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.1

Lunar Motions The lunar orbital plane does not coincide with earth’s orbital plane. Approximately 5o with respect to earth’s orbital plane. Due to this 5o tilt, it is possible for the moon to be directly overhead at any latitude between 28.5oN and 28.5oS. Both the rotation of the earth on its axis and the moon’s revolution around the earth are counterclockwise (from a N pole perspective). Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Relative Motions of the Moon and Earth
Section 17.2

Two Different Lunar Months
Sidereal Month – days, lunar cycle with respect to a star other than the sun Synodic Month – 29.5 days, lunar cycle with respect to the sun From one’s perspective on earth the synodic month is one complete month of lunar phases. In actuality the moon revolves more than 360o during a synodic month. From earth it appears that every day the moon rises in the east and sets in the west. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Phases of the Moon The moon’s periodic change in appearance is its most outstanding visual feature. One-half of the moon is always reflecting light from the sun, but only once during that cycle can an observer on earth see the entire illuminated half, called a “full moon.” The starting point for the moon’s synodic month is arbitrarily taken a the “new moon” position. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

New Phase or New Moon Occurs when earth, sun, and moon are all in the same plane, with the moon positioned between the Sun and Earth At this position, the dark side of the moon is fully toward the Earth (“dark of the moon”). Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Lunar Phase Vocabulary
Waxing phase - the illuminated portion is getting larger Waning phase – the illuminated portion is getting smaller Crescent moon – less than ½ of the visible portion of the moon is illuminated Gibbous moon – more than ½ of the visible portion of the moon is illuminated Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Phases of the Moon As observed from any latitude north of 28.5oN
The “observer” is looking south; therefore east is on the left. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Waxing Phases of the Moon
Waxing crescent phase – appears as a crescent moon, less than 90o east of sun (7.375 days) First-quarter phase – when the moon is exactly 90o east of sun Waxing gibbous phase – appears larger than ½ illuminated, but < a full moon (7.375 days) Full Moon – 180o Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Waning Phases of the Moon
Waning gibbous phase – appears < a full moon, but larger than ½ moon (7.375 days) Last-quarter phase – when the moon is exactly 270o east of sun Waning crescent phase – appears smaller than ½ illuminated (7.375 days) New Moon – 360o Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Altitude of the Full Moon
A full moon is always on the opposite side of the earth from the sun. Thus when the sun is at its lowest position (winter solstice), the moon will be at its highest. Due to the 5o difference in the earth’s and moon’s orbital planes, the moon will be situated directly over the 28.5o N latitude line on the winter solstice. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Eclipses The sun provides the light for our solar system
Planets and moons within the solar system cast shadows that extend away from the sun The size and shape of the shadow cast depends on the object’s size, shape, and distance from the sun The Earth and the Moon cast conical shadows, as viewed from space Eclipse – the darkening of the light of one celestial body by another Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Eclipses The shadows cast by the Earth and the Moon cast two different degrees of darkness Umbra – the darkest and smallest region A total eclipse occurs within the umbra region Penumbra – the semidark region A partial eclipse occurs within the penumbra region Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Solar Eclipse Solar eclipse – occurs when the moon blocks some or all of the sun’s rays from an observer on Earth A solar eclipse occurs when the moon is at or near new phase and is in or near the ecliptic plane When the moon lies between the sun and Earth in nearly a straight line, the moon’s shadow will fall on the Earth Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Positions of the Sun, Moon, and Earth During a Total Solar Eclipse
The umbra and penumbra are, respectively, the dark and semidark shadows cast on the Earth by the Moon Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Types of Solar Eclipses
The length of the moon’s shadow varies with the moon’s distance from the sun In some cases the moon’s umbra does not reach all the way to Earth If the umbra does not reach Earth, an observer on Earth would see the moon’s disk projected against the sun and a bright ring or annulus outside the dark moon – this is called an annular eclipse The maximum diameter of the umbra on Earth is about 270 km Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Lunar Eclipse Lunar eclipse - occurs when the Earth blocks some or all of the sun’s rays to the moon A lunar eclipse occurs when the moon is at or near full phase and is in or near the ecliptic plane When the Earth lies between the sun and moon in nearly a straight line, the Earth’s shadow will conceal the face of the moon A total lunar eclipse can last for more than 1.5 hours, and partial eclipses may last for over 3 hours Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Intersection of the Orbital Planes of the Earth and the Moon
There is a 5o8’ Angle between the Orbital Planes of the Earth and the Moon Therefore, the paths of the two planes intersect at only two points during the monthly cycle The points where the moon’s path crosses the ecliptic are called the nodes Ascending node – the point of crossing going northward Descending node – the point of crossing going southward Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Ocean Tides Tides – the regular and alternating rise and fall of the ocean’s surface level Although by the 1st century people had noticed the relationship between the passage of the moon and the tides, no one could explain why Finally in the 17th century Newton applied his law of universal gravitation to explain the ocean tides by the motions of the Earth, moon, and sun Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Tidal Bulges The two tidal bulges result in two high tides and two low tides daily
Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Ocean Tides One of the tidal bulges is caused by the moon’s gravitational attraction on the side of the Earth nearest to the moon Another tidal bulge is located on the side of the Earth farthest away from the moon This distant tidal bulge is caused by the force of gravity pulling the Earth away from the water on the distant side, forming a second and opposite bulge Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Spring Tide Spring tide occurs when the sun, moon, and Earth are all positioned in nearly a straight line In this situation, the gravitational forces of the sun and moon combine to produce higher high tides and lower low tides The variations between high and low tides are the greatest during a spring tide Spring tides occur twice during each lunar month; at new and full moons Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Neap Tide Neap tide occurs when the sun and the moon are at angles of 90o with respect to the Earth In this situation, the gravitational forces of the sun and moon tend to cancel and produce lower high tides and higher low tides The variations between high and low tides are at a minimum during the neap tide Neap tides occur twice during each lunar month; at first and last quarter Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Tidal Height Varies The height of the tide also varies with latitude
The two tidal bulges are the highest at the latitude of the overhead position of the moon and on the other side of the Earth opposite the moon’s position Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Spring Tide During Summer Solstice
The maximum height of the tidal bulge is at 23.5oN and 23.5oS, due to the overhead position of the moon and the sun on this day Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Tidal Effects on the Earth/Moon System
The regular tidal cycle retards the Earth’s rotation at a rate of about s per century Since angular momentum must be conserved, this decrease in Earth’s angular momentum results in an increase in the moon’s angular momentum The moon’s orbit is increasing about 1.3 cm/y If we went back 1 billion years, the solar day would have been 5.6 h shorter, and the moon would have been 13,000 km closer to Earth Copyright © Houghton Mifflin Company. All rights reserved. Section 17.2

Moons of the Jovian Planets and Pluto
Jupiter: 62 known moons 1. Io 2. Europa 3. Ganymede 4. Callisto 5. Amalthea 6. Himalia 7. Elara 8. Pasiphae 9. Sinope 10. Lysithea 11. Carme 12. Ananke 13. Leda 14. Thebe 15. Andrastea 16. Metis 17. Callirrhoe 18. Themisto 19. Megaclite 20. Taygete 21. Chaldene 22. Harpalyke 23. Kalyke 24. Iocaste 25. Erinome 26. Isonoe 27. Praxidike 28. Autonoe 29. Thyone 30. Hermippe 31. Aitne 32. Eurydome 33. Euanthe 34. Euporie 35. Orthosie 36. Sponde 37. Kale 38. Pasithee 39. Hegemone 40. Mneme 41. Aoede 42. Thelxinoe 43. Arche 44. Kallichore 45. Helike 46. Carpo 47. Eukelade 48. Cyllene 49. Kore 50. S/2003 J2 51. S/2003 J S/2003 J S/2000 J S/2003 J S/2003 J S/2003 J12 57. S/2003 J S/2003 J S/2003 J S/2003 J S/2003 J S/2003 J23 Copyright © Houghton Mifflin Company. All rights reserved. Section 17.4

The Galilean Moons of Jupiter

Saturn: 59 known moons 1. Mimas 2. Enceladus 3. Tethys 4. Dione 5. Rhea 6. Titan 7. Hyperion 8. Iapetus 9. Erriapo 10. Phoebe 11. Janus 12. Epimetheus 13. Helene 14. Telesto 15. Calypso 16. Kiviuq 17. Atlas 18. Prometheus 19. Pandora 20. Pan 21. Ymir 22. Paaliaq 23. Tarvos 24. Ijiraq 25. Suttungr 26. Mundilfari 27. Albiorix 28. Skathi 29. Siarnaq 30. Thrymr 31. Narvi Methone 33. Pallene 34. Polydeuces 35. Daphnis 36. Aegir 37. Bebhionn 38. Bergelmir 39. Bestla 40. Ferbauti 41. Fenrir 42. Fornjot 43. Hati 44. Hyrokkin 45. Kari 46. Loge 47. Skoll 48. Surtur 49. S/2004 S7 50. S/2004 S S/2004 S S/2004 S S/2006 S S/2006 S3 55. S/2006 S S/2006 S S/2007 S1 58. S/2007 S S/2007 S3 Copyright © Houghton Mifflin Company. All rights reserved.

Saturn: 35 known moons—Titan, the largest

Uranus: 27 known moons 1. Cordelia 2. Ophelia 3. Bianca 4. Cressida 5. Desdemona 6. Juliet 7. Portia 8. Rosalind 9. Mab 10. Belinda 11. Perdita 12. Puck 13. Cupid 14. Miranda 15. Francisco 16. Ariel 17. Umbriel 18. Titania 19. Oberon 20. Caliban 21. Stephano 22. Trinculo 23. Sycorax 24. Margaret 25. Prospero 26. Setebos 27. Ferdinand Copyright © Houghton Mifflin Company. All rights reserved.

Moons of the Jovian Planets
Neptune: 13 known moons 1. Triton 2. Nereid 3. Naiad 4. Thalassa 5. Despina 6. Galatea 7. Larissa 8. Proteus 9. Halimede 10. Psamathe 11. Sao 12. Laomedeia 13. Neso Copyright © Houghton Mifflin Company. All rights reserved.

Eris One known moon, Dysnomia Diameter is estimated to be 1/8 of Eris
Orbital period about 14 days Astronomers are trying to determine mass Copyright © Houghton Mifflin Company. All rights reserved.

Other Solar System Objects:
Asteroids – minor planets Believed to be early solar system material that never collected into a single planet Range in size from 940 km in diameter (Ceres) to Millions estimated to be in Asteroid Belt >20,000 named and numbered in the Asteroid Belt In 2001, a spacecraft actually landed on the asteroid Eros which approaches the Earth to within 1 AU. This asteroid is about the size and shape of the island of Manhattan. Copyright © Houghton Mifflin Company. All rights reserved. Section 17.5

NEAR – Near Earth Asteroid Rendezvous The NEAR spacecraft landed on the asteroid Eros on 2/12/01. It transmitted 69 close-up images of the surface during its final descent. Copyright © Houghton Mifflin Company. All rights reserved.

Asteroids or Minor Planets

Micrometeorids or Interplanetary Dust Two celestial phenomena: Zodiacal light—a faint band of light along the zodiac. Gegenshein “counterglow”—due to sunlight reflected from dust particles Copyright © Houghton Mifflin Company. All rights reserved.

Moons and Other Solar System Objects

Similar presentations

Presentation on theme: "Moons and Other Solar System Objects"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Moons and Other Solar System Objects

Similar presentations

Presentation on theme: "Moons and Other Solar System Objects"— Presentation transcript:

Similar presentations

About project

Feedback