NATS 1311 From the Cosmos to Earth Properties

NATS 1311 From the Cosmos to Earth Properties of Waves Period: time to complete one cycle of vibration (From 1 to 5) Frequency (f): number of crests passing a fixed point per second Frequency= 1/period Example: Period = 1/100 = 0. 01 sec. Frequency = 100 hertz (cycles/sec. )

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth Amplitude (a): maximum displacement from Equilibrium Wave length (l): distance between successive crests (2 to 6, 4 to 8, etc. . . ) Speed (of a wave) (s)= wave length x frequency s= l x f

NATS 1311 From the Cosmos to Earth TYPES OF WAVES Transverse: Vibration or oscillation is perpendicular to direction of propagation of wave. Examples: water wave, vibrating string Longitudinal: Vibration or oscillation is in the same direction as propagation of wave. Examples: sound waves, mass on a spring, loudspeaker

NATS 1311 From the Cosmos to Earth ELECTROMAGNETIC WAVES (LIGHT WAVES) Velocity 186, 000 miles/second 300, 000 kilometers/second 3 x 1010 cm/second • It takes 1 1/3 second for light to travel from the earth to the moon. • It takes 8 1/3 minutes for light to travel from the sun to the earth.

NATS 1311 From the Cosmos to Earth ELECTROMAGNETIC WAVES (LIGHT WAVES) Speed of propagation of a light wave: c=lxf c = velocity of light; c is a constant in vacuum l = wavelength of a light wave - distance between successive crests f = frequency of a light wave - number of crests passing a fixed point in 1 second

NATS 1311 From the Cosmos to Earth PHOTON • Light propagates as quanta of energy called photons • Photons • move with speed of light • have no mass • are electrically neutral • Energy of a photon or electromagnetic wave: E = hf = h c/ l where h = Planck’s constant f = frequency of a light wave - number of crests passing a fixed point in 1 second c = velocity of light l = wavelength of a light wave distance between successive crests

NATS 1311 From the Cosmos to Earth FIG. 6. 4 Figure 6. 4 The electromagnetic spectrum. The unit of frequency, hertz, is equivalent to waves per second. For example, 103 Hz means that 103 wave peaks pass by a point each second.

NATS 1311 From the Cosmos to Earth Absorption and Emission. When electrons jump from a low energy shell to a high energy shell, they absorb energy. When electrons jump from a high energy shell to a low energy shell, they emit energy. This energy is either absorbed or emitted at very specific wavelengths, which are different for each atom. When the electron is in a high energy shell, t he atom is in an excited state. When the electron is in the lowest energy shell, the atom is in the ground state.

NATS 1311 From the Cosmos to Earth The Hydrogen Atom. The hydrogen atom is the simplest of atoms. Its nucleus contains only one proton which is orbited by only one electron. In going from one allowed orbit to another, the electron absorbs or emits light (photons) at very specific wavelengths.

NATS 1311 From the Cosmos to Earth Fig. 6. 6 Figure 6. 6 (a) Photons emitted by various energy level transitions in hydrogen. (b) The visible emission line spectrum from heated hydrogen gas. These lines come from transitions in which electrons fall from higher energy levels to level 2. (c) If we pass white light through a cloud of cool hydrogen gas, we get this absorption line spectrum. These lines come from transitions in which electrons jump from energy level 2 to higher levels.

NATS 1311 From the Cosmos to Earth Kirchhoff’s Laws of Radiation First Law. A luminous solid, liquid or gas, such as a light bulb filament, emits light of all wavelengths thus producing a continuous spectrum of thermal radiation. Second Law. If thermal radiation passes through a thin gas that is cooler than thermal emitter, dark absorption lines are superimposed on the continuous spectrum. The gas absorbs certain wavelengths. This is called an absorption spectrum or dark line spectrum. Third Law. Viewed against a cold, dark background, the same gas produces an emission line spectrum. It emits light of discrete wavelengths. This is called an emission spectrum or bright line spectrum. .

NATS 1311 From the Cosmos to Earth Fig. 6. 11 This diagram illustrates Kirchhoff’s laws of radiation.

NATS 1311 From the Cosmos to Earth FIG. 6. 19 Figure 6. 19 The basic design of a spectrograph.

NATS 1311 From the Cosmos to Earth Fig. 6. 7 Figure 6. 7 Emission line spectra for helium, sodium, and neon. The patterns and wavelengths of lines are different for each element, giving each a unique spectral fingerprint.

NATS 1311 From the Cosmos to Earth Fig. 6. 13 Figure 6. 13 The Doppler effect. (a) Each circle represents the crests of sound waves going in all directions from the train whistle. The circles represent wave crests coming from the train at different times, say, 1/10 second apart. (b) If the train is moving, each set of waves comes from a different location. Thus, the waves appear bunched up in the direction of motion and stretched out in the opposite direction. (c) We get the same basic effect from a moving light source.

NATS 1311 From the Cosmos to Earth Fig. 6. 14 Figure 6. 14 Spectral lines provide the crucial reference points for measuring Doppler shifts.

NATS 1311 From the Cosmos to Earth Lenses and Mirrors Object distance: do distance from lens or mirror to object. Image distance: di distance from lens or mirror to image Focal length: Distance from lens or mirror to image when the object is at infinity (a long distance away). Lens formula:

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth Lens and Mirror Aberrations SPHERICAL (lens and mirror) Light passing through different parts of a lens or reflected from different parts of a mirror comes to focus at different distances from the lens. Result: fuzzy image CHROMATIC (lens only) Objective lens acts like a prism. Light of different wavelengths (colors) comes to focus at different distances from the lens. Result: fuzzy image

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth FIG. 6. 15 Figure 6. 15 (a)The basic design of a refracting telescope. (b)(b) The 1 meter refractor at the University of Chicago's Yerkes Observatory is the world's largest refracting telescope.

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth FIG. 6. 17 Figure 6. 17 Alternative designs for reflecting telescopes.

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth FIG. 6. 20 Figure 6. 20 Observatories on the summit of Mauna Kea in Hawaii. The twin domes near the far right house the two Keck telescopes.

NATS 1311 From the Cosmos to Earth FIG. 6. 25 Figure 6. 25 The Arecibo radio telescope in Puerto Rico is the world's largest single radio dish.

NATS 1311 From the Cosmos to Earth FIG. 6. 21 Figure 6. 21 This diagram shows the basic components of the Hubble Space Telescope, which orbits the Earth. The entire observatory is roughly the size of a school bus.

NATS 1311 -From the Cosmos to Earth Solar System % Mass of Solar System Sun 99. 85% Jupiter 00. 10% Others 00. 05% Terrestrial Planets: • Mercury, Venus, Earth, Mars – Rocky, Silicates, Metals Jovian Planets: • Jupiter, Saturn, Uranus, Neptune, Pluto (icy moon) – Gases, Liquids

NATS 1311 -From the Cosmos to Earth Solar System Figure 7. 1 Side view of the solar system. Arrows indicate the orientation of the rotation axes of the planets and their orbital motion. (Planetary tilts in this diagram are aligned in the same plane for easier comparison. Planets not to scale. ) Seen from above, all orbits except those of Mercury and Pluto are nearly circular. Most moons orbit in the same direction as the planets orbit and rotate--counterclockwise when seen from above Earth's North Pole.

NATS 1311 From the Cosmos to Earth Full moon

NATS 1311 From the Cosmos to Earth Moon Distance from earth: Diameter: Mass moon/mass earth: Density: Gravity: 238, 000 miles 2100 miles (1/4 earth) 0. 012 3. 34 gm/cm 3 1/6 that of earth

NATS 1311 From the Cosmos to Earth Moon Appearance: §Highlands - heavily cratered §Maria- smoother §Mountain ranges §Rilles - clefts in surface §Craters Diameter 200 miles to 1 millimeter Rims higher than grand canyon §Rotation - phase locked to earth §Synodic period - 29 1/2 days §Sidereal period - 27 1/3 days §Surface - igneous rocks - cooled lava

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth

Apollo 17 Lunar Mass Spectrometer on surface of moon.

Close-up of mass spectrometer on lunar surface. Apollo 17 mass spectrometer found principal gases in atmosphere to be hydrogen, neon and argon.

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth South pole of moon

NATS 1311 From the Cosmos to Earth South pole craters

NATS 1311 From the Cosmos to Earth Silver spur

NATS 1311 From the Cosmos to Earth Lunar rover

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earthrise as seen from the moon

NATS 1311 From the Cosmos to Earth Apollo lunar exploration results 1. Surface composition Earth - like rocks but not exactly Basalt - rapidly cooled lava - abundant on Earth Anorthosite- more slowly cooled lava- found Principally in adirondac mountains Breccias - mixture of fragments of other types of rocks Kreep - potassium, rare earth, phosphorus Rocks found in highlands mounts Soils - contain tiny glass beads - elements with High melting points No water Regolith - ground up rock

NATS 1311 From the Cosmos to Earth 2. Chronology Moon formed 4. 6 billion years (by) ago Oldest rocks - 4. 4 by Youngest rocks - 3. 1 by Volcanism from 3. 8 to 3. 1 by ago internal heating Moon dead for last 3. 1 by 3. Interior Core - probably molten metal Mantle - silicate materials Crust 40 mile thick on near side 80 mile thick on far side Mascons - regions of high gravity under the maria

NATS 1311 From the Cosmos to Earth 4. Origin - 4 theores, first three have problems listed below each theory 1. Fission - moon split off from earth chemical dissimilar low iron in moon angular momentum 2. Capture - came from elsewhere in solar system orbital mechanics chemical similarities - low iron in moon 3. Double planet - both formed locally chemical differences angular momentum

NATS 1311 From the Cosmos to Earth 4. Giant lmpact - Body 10% size of earth impacted young earth at a grazing angle. Melted but threw off layer of material that condensed into moon. ~ Most likely theory. 5. Atmosphere Very rarified Pressure: one 100 th of one trillionth of earth (10 -14 of earth) A very good vacuum Composition: mostly noble gases

NATS 1311 From the Cosmos to Earth Fig. 7. 9 Figure 7. 9 Artist's conception of the impact of a Mars-size object with Earth, as may have occurred soon after Earth's formation. The ejected material comes mostly from the outer rocky layers and accretes to form the Moon, which is poor in metal.

NATS 1311 From the Cosmos to Earth Mercury Property Earth Mercury 1 0. 4 5. 5 5. 4 1 0. 4 365 88 1 59 23. 5° 7° Inclination of orbit to ecliptic plane 0° 7° Maximum angle from sun ~ 28° Surface temperature ~ Day: 800°F ~ Night: -280°F 1 atmosphere 10 -15 atmosphere N 2 , O 2 Helium, sodium, potassium, oxygen Equatorial Diameter Density (gm/cm 3) Avg. Distance from Sun (AU) Orbital Period (days) Sidereal Rotation Period (days) Inclination of axis to orbital plane Atmosphere - pressure Atmosphere - composition

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth The orbit of Mercury At an average distance of only 58 million kilometers (36 million miles) from the sun, mercury takes a mere 88 days to go around its orbit. As viewed from earth, mercury can be seen only near times of greatest eastern or western elongation. At greatest western elongation (when the planet is farthest west of the sun in the sky), mercury rises about 1 1/2 hours before sunrise. At greatest eastern elongation (when the planet is farthest east of the sun in the sky), mercury sets about 1 1/2 hours after sunset.

NATS 1311 From the Cosmos to Earth

NATS 1311 From the Cosmos to Earth Mariner 10 view of Mercury, March 29, 1974 from 125, 000 miles away

NATS 1311 From the Cosmos to Earth Mercury, Mariner 10 photo. Large valley to right is 4 miles wide and 60 miles long. It leads into crater 50 miles in diameter.

NATS 1311 From the Cosmos to Earth Mercury. Picture taken form 3700 miles away. Relatively level surface resembles mare regions of moon.

NATS 1311 From the Cosmos to Earth Mercury. Long scarp diagonally across picture.

NATS 1311 From the Cosmos to Earth Mercury. Crater at lower left is 40 miles in diameter. Slows flow front extending across crater floor.

NATS 1311 From the Cosmos to Earth Differences between the Moon and Mercury 1. Areas between craters on Mercury smoother than on Moon. 2. Secondary impact craters don't scatter as much on Mercury. 3. Gravitational acceleration on Mercury twice that of moon. 4. Mercury has scarps - caused by shrinkage of its surface. 5. Mercury's atmosphere consists of sodium and potassium (sputtered form surface by the solar wind), helium and oxygen. 6. Atmospheric pressure about the same as on the Moon.