Astronomy 2140 - Autumn 2024 - MWF - 11:30-12:25 - Evans lab EL2004

DAILY TOPICS

SYLLABUS: 11:30-12:25

Mid Term exams are on the material covered in class.

The textbook mentioned in the syllabus is not required but recommended. In case you have it, we shall be covering Chapters 1 - 12 in the recommended textbook. However, some of those topics will not be covered in class. You should know the material we do cover in class, so read corresponding material in the textbook.

Requied reading material is mandatory albeit with considerable flexibiliy as to its source in addition to the ones listed on the syllabus.

Fieldwork_Homework via planetarious shows and writeups is also mandatory.

The first half of the course, up to the second quiz deals with the basic concepts in astronomy, indeed science in general. The material refers to the work by ancient Greeks (use of Geometry), through the "Dark Ages (500-1200 AD) to Copernicus (Helio-centric model - Sun is the center of the planetary system}, and on to Galileo,Tycho, and Kepler. They laid the foundation for further theoretical and observational development of astronomy (science!) through the work of Newton and up to Einstein. We shall finish the period leading up to Quiz 2 with studies of light, spectra, atoms and their inter-relationships. The Textbook covers nearly all of this, and more, but the material is spread over several chapters. Please consult the index for the material covered in class. All of the chapters and pages are not listed in the outline of the course (which is only approximate) since there is no direct correspondence.

The second half of the course is more specific in the sense that we shall mainly be studying the detailed properties of Planets. Also, there are many details (as opposed to basic laws). Most (but not all) of the topics covered in class will therefore be posted herein, as below.

The exam questions will be largely from material covered in class. The daily topics listed below cover only the main points. Make sure to read your notes and the corresponding recommended and required material.

• Aug 21, Wednesday: Overview of syllabus; no proven connection between astrology and astronomy; since stars also move, the position of the Sun relative to the 12 Constellations of the Zodiac changes over centuries and is different from the dates given in the 'horoscope' section of newspapers; science and religion: faith vs. inquiry; ancient astronomy; use of Geometry by the Greeks, belief in the Geocentric system (Aristotle,Ptolemy), Geocentric model (Ptolemy) vs. the Heliocentric model (Copernicus).
• Aug 23, Friday: Astronomy overview: stars, galaxies, nebulae, size scales in the Universe. Two basic groups of planets: Terrestrial (hotter, solid surface) planets (Mercury, Venus, Earth, Mars) closer to the Sun, and Jovian (colder, giant, gaseous) planets (Jupiter, Saturn, Neptune, Uranus) farther out. Pluto is more like a moon, but does orbit the Sun like a planet. But many other objects now known to be beyond Pluto and also orbiting the Sun; basic fundamental constants such as speed of light, 1 AU = (E-S) distance, etc.; the Celestial Sphere - stars 'fixed' in the Sky as a globe; the distance scale; physical and angular distances and sizes; distance measures in astronomy are the AU and the Light year (LY); Ecliptic - path of the Sun in the Sky; Celestial Equator - extension of Earth's equator to the celestial sphere. Angular distance and size. The Earth moves about 1 degree in its orbit around the Sun each day. Another distance unit is based on the method of parallax - the apparent change in angular position due to motion; define 1parsec (pc) = 1/alpha(arcseconds), where alpha is the angle usually mesured relative to the orbit of the E-S orbit; 1 pc = 3.26 LY.
• Aug 26 Monday: Vernal (Spring) and Autumn Equinoxes and Summer and Winter Solstices, related to seasons. Celestial 'longitude' - Right Ascension, Celestial 'latitude' - Declination, enable the location of an object in the Sky.
• Aug 28, Wednesday: Ptolemy, Aristotle - All heavenly objects revolve around the Earth, with planets also describing Epicycles that account for the observed Retrograde Motion of outer (Superior) planets such as Mars; Eratosthenes's measurement of Earth's circumference. HELIOCENTRIC MODEL (COPERNICUS) - The Sun is at the Center with all planets revolving around it in circular orbits (not quite correct, but basically right); Inferior Planets (Mercury, Venus) - orbits inside the Earth's orbit (inferior and superior conjuction), Superior Planets (Mars,Jupiter,etc.) with orbits outside (opposition and superior conjunction); synodic (apparent) and Sidereal (w.r.t. stars) periods of revolution of planets around the Sun; e.g. Synodic period of Jupiter is 399 days, but its sidereal period is 11.9 years; the Copernican System - determination of relative distances of planets from the Sun from the angle of greatest eastern and western elongation (the maximum angular separation of the planet from the Sun as seen from the Earth). Fieldwork+Homework --> Walk among the markers of the Sun and the eight planets on Woodruff Avenue in carefully measured steps and calculate the ratio of Sun-planet distances; compare with Copernican values in a table that gives the number of steps as data. Assignment due on or before Sep 17 to be submitted via Carmen.
• Aug 30, Friday: Planetarium show at class time, 5th Floor Smith Lab. No class. Homework due a week from now: 10-point summary of your understanding of the contents of the show.
• Sep 4, Wednesday: PHASES OF THE MOON - Horns of a crescent moon always point away from the Sun; phases of the Moon may be used to keep track of days of the month, as well as approximate time; the new moon rises and sets with the Sun, the full moon rises at sunset, the first qtr moon rises at noon, and so on. Seasons occur due to the 23.5 degree tilt in the Earth's rotation N-S axis (NOT because the Earth is closer or farther from the Sun). ECLIPSES - due to the Moon in between the E and the S (solar eclipse), or the Earth between M and S (lunar eclipse); total or partial eclipses depending on the Umbra or the Penumbra. Solar eclipse during new moon, and total lunar eclipse during full moon; we don't have eclipses every month because the moon's orbital plane around the Earth is inclined at 5 degrees to the Earth's orbital plane around the Sun; eclipses occur when the E-M-S are along the line-of-nodes; total lunar eclipse more common since it can be seen from the entire night side of the Earth, but total solar eclipse is only seen from a narrow band across the Earth, at most about 269 KMs wide. One Day - period of rotation of the Earth on its axis - Sidereal (w.r.t. stars) and solar (w.r.t.Sun) - sidereal day is 4 mins. shorter; Calendar - Lunar and Solar, but inconsistent with each other; one month is taken to be the Moon's period of revolution around the Earth = 29.5306 days; but 12 times this does NOT equal one year = 365.2422 days; Two problems: (i) a calendar can not be based on both the Moon and the Sun; Lunar calendar is not widely used; (ii) the year is not an exact number of days - Roman (Julian) Calendar with one extra day every 4 years (Leap Year); but that overcorrect by 11 min./year; Gregorian Reform; Century years NOT divisible by 400 are NOT Leap Years, e.g. 1700 AD was not a Leap Year, but 2000 AD was. Motions of the Earth: Rotation on its axis (1 day), revolution around the Sun (1 year), precession of the N-S axis (26,000 years); position of the North Star will change due to precession; Polaris will no longer be the North Star a few thousand years from now.
• Sep 6, Friday: TYCHO: Pre-telescopic observer; made accurate measurements of Mars with Kepler as assistant. KEPLER's LAWS: First Law - planetary orbits are elliptical with the Sun at one focus; `eccentricity' (ellipticity) e = distance from center to a focus/ semi-major axis. Kepler's Laws (Contd.): Second law - planets trace out equal area triangles in equal time ('equal triangles law'); Third law - P-squared = a-cubed, or P*P = a*a*a, where P is the period in years, and a is the semi-major axis of the orbit in AU. The Earth and the Moon (or any two objects orbiting under gravity) revolve around a common center of mass called the Barycenter that lies 1700 kms inside the Earth. GALILEO: defended the Copernican Heliocentric system; first one to use the telescope; made many discoveries to support the Heliocentric model - phases of Venus, moons of Jupiter, Sunspots; also discovered mountains on the Moon, found that the Milky way is made of stars, etc; Galileo did pioneering experiments on gravity - "all things fall at the same rate regardless of weight or mass".
• Sep 9, Monday: Newton's Law of GRAVITATION - F (grav) = G * (m1*m2)/(r*r), i.e. the force of gravity between two masses is directly proportional to their product, and inversely proportional to the square of the distance between them; your weight is the force of gravity between you and the Earth, i.e. F = G * m(you) * M(Earth) / R(Earth)-squared; the constant G is known as the Universal gravitation constant and is the same for all masses in the Universe; Escape velocity, kinetic and potential energy, orbits, angular momemtum. "Escape veloctiy" is the velocity needed to escape the gravity of the Earth = 11 Km/sec; Orbiting objects are continuosly 'falling', such as the Moon is continuously falling towards the Earth, which curves away from it at the same rate.
• Sep 11, Wednesday: Popquiz 1, 5 questions at end of class
• Sep 13: Mid-term quiz 1, 35 questions in 45 minutes via Carmenzoom
• Sep 16, Monday: TIDES - due to the differential force of gravity of the Moon across the Earth; therefore have tides on opposite sides of the Earth, the side nearest the Moon accelerates fastest towards it, but the farthest side 'gets left behind", relative to the Center of the Earth; Both the Moon and the Sun cause tides, but the Sun's influence is weaker; however, strongest tides (spring tides) during full and new moon when the the Sun's and Moon's gravitational forces add together, and weakest tides (neap tides) during quarterly lunar phases. Ch. 6: Earth's rotation - proof by Foucault's pendulum (visit COSI !); the pendulum swings irrespective of the rotation of the support in a line, but traces out a circle on the floor due to rotation of the Earth. Consequences of Earth's rotation - cyclones caused by hot winds from warmer equatorial regions rising north, where they have a faster relative eastward velocity (the speed of rotation at the Equator is 1700 kms/hr, but at the poles it is zero); this is an example of the Coriolis force due the uperpostion of linear motion (winds moving up-down, N-S) and rotational motion (of the Earth), such as experienced in a rotating carousel (merry-go-round); fast winds may spiral into low-pressure areas causing hurricanes, cyclones etc., like water going down a bathtub drain; All rotating or revolving object have angular (rotational) momemtum L = m x v x r (mass times velocity times distance from the center or axis of rotation); L is conserved, or remains constant; therefore if r decreases then v must increase, and vice versa; that's why an ice skater speeds up while spinning when (s)he pulls her/his arms inwards; Other examples include helicopter rotor, spinning top, etc.; the axis of a spinning top "wobbles" or "precesses" slowly in a circle if it is tilted while spinning, instead of falling down; the precession of the Earth's axis is another example; L acts as a stabilising quantity, e.g. a gyroscope (basically a spinning wheel) inside a satellite or spacecraft acts to stabilise it and point in a certain direction (say towards a star).
• Partial Study Guide Quiz 1
• Sep 18, Wednesday: Einstein's Theory of RELATIVITY: First Postulate - speed of light 'c' is a universal constant independent of the velocity of the source or the observer; Second Postulate - All physical laws have the same form everywhere in the Universe; E = m*c-squared, i.e. mass and energy are equivalent; mass (inertia) increases with velocity; it takes an infinite amount of energy to accelarate any mass to 'c' - therefore impossible for an object (e.g. spacecraft) to travel at the speed of light; The Special Theory deals with velocity; the General Theory of Relativity deals with acceleration; Principle of Equivalence - acceleration and gravitation are equivalent; Astronauts are weightless because they are falling at the same rate as the floor of the shuttle in orbit; time 'flows' slower for a moving object (astronauts live slightly longer!).
• Sep 20, Friday: LIGHT and MATTER, Ch 4: MATTER and ATOMS: Matter is made of 92 naturally occuring elements (and some artificially made in the laboratory). Atoms are the smallest particle with the same characterstic as the element; atoms are made of positively charged protons and neutral neutrons in the center called the nucleus, surrounded by negatively charged electrons. LIGHT - electromagnetic energy.
• Sep 23, Monday: LIGHT (Contd.): Spectrum of visible light, blue to red; waves and wavelength. Light does not require a medium to propagate (unlike water or sound waves); particle of light are photons; c = wavelength x frequency; color depends on wavelength; blue light has higher frequency, hence shorter wavelength, than red light; the e.m. spectrum extends from gamma rays (highest frequency) to radio waves (longest wavelengths); visible light is a small part of the spectrum, from blue (4000 A) to red (7000 A), where A is the Angstrom unit = 100 millionth of a cm; the hotter an object the more energetic ("bluer") its light, and vice versa. Spectrum of visible light, Atoms and Light -- photons have energy E = h * nu, where nu is the frequency = c/wavelength (h is called the Planck's Constant); each photon has a definite wavelength and hence 'color'.
• Sep 25, Wednesday: MATTER - ATOMS and SPECTRA - Quantum Theory: The positively charged nucleus is surrounded by negatively charged electrons arranged in definite and discrete energy orbits. Electrons can absorb or emit photons at definite energies (wavelengths) equal to the energy difference between orbits e.g. H-atom has one electron and one proton. An electron in H-atom emits photon at wavelength 6562 Angstroms (red color!) when jumping from the third to the second orbit. SPECTRUM of a source (e.g. the Sun) is its light resolved according to lines at characterstic wavelengths. Emission spectrum is bright `color' lines, i.e. light emitted by atoms at certain wavelengths; and absorption spectrum is dark lines i.e. energy removed by atoms at corresponding wavelengths. Demostration: Emission spectra from fluorescent Tubes with H, He, Ne, Hg, H2O, CO2, Ar. Continuous, absorption, and emission spectra from astronomical objects; spectra outside the visible range (say X-ray) is not seen by human eye, but may be present nonetheless.
• Sep 27, Friday: *** Spectroscopy demonstration of emission lines ***
• Sep 27, Friday: Color and Temperature - The Sun has a surface temperature of 5600 K and emits its peak light at yellow color. TEMPERATURE: Kelvin and Celsius temperature scales; room temperature is about 300 K; Temperature T of `blackbodies' - perfect radiators and absorbers at one T, with peak radiation at one wavelength. Brightness (luminosity) increases as temperature to the fourth power; brigtness of a source decreases as the inverse of the distance; Inverse Square Law due to geometry -- the area of a sphere increases as 4*pi*radius-squared. DOPPLER Effect, and Red- and Blue-shift. Monday: Hubble's Law: v = H_o d --> velocity increases with distance of galaxies; implies expansion of the Universe; H_o is Hubble's constant; 1/H_o is the age of Universe.
• Sep 30, Monday: Observatories and Telescopes; two kinds - reflecting (mirrors) and refracting (lenses); the main purpose of a telescope is to collect and focus light (not to magnify the image); the `OBJECTIVE' is the primary mirror or lens; `power' of a telescope refers to the diameter of the Objective; various designs of optical telescopes; The two Keck telescopes are the largest in the world, each 10 m diameter; Ohio State is part of the Large Binocular Project (LBT) with twin 8.4 m telescopes; the Hubble Space Telescope (HST) has a 2.4 m mirror; Astronomy requires ground and space based observations in all wavelength ranges; need space based observatories since only the visible, near-IR, and radio waves penetrate the Earth's atomosphere; other wavelength ranges such as UV and X-ray require satellite observations. Optical telescopes: mirrors and lenses. Lenses not used in modern telescopes owing to Chromatic Aberration. Properties of Refraction and Reflection.
• Oct 2, Wednesday: Tuesday: PLANETS Overview. TERRESTRIAL - rocky, metallic, with Refractory elements such as Si, S, Fe; density ~ 3-5.5 g/cc, hotter and smaller than JOVIAN planets - cool and massive with volatile elements, mainly H, He, density 1-2 g/cc, which escaped from the nearer terrestrial planets. Planetary atmospheres - Terrestrial and Jovian planets; comparison and contrast; unique features of each of the eight planets, and Pluto.
• Pop quiz #2
• Oct 4, Friday: Mid-term exam 2. The following study guides cover many of the topics thus far, but not all of the material in the lecture notes and the daily outline. Partial Study Guide Quiz 1, Partial Study Guide Quiz 2
• Oct 7, Monday: planetarium show during class time.
• Oct 7, Monday: *** See Important Announcement on Carmen ***
• Oct 9, Wednesday: Special lecture on Carmenzoom. Passcode to attend lecture 720230 is needed. Starting class time at 11:30 AM, but can log in a few minutes early. EARTH: Atmospheric layers - Troposphere: clouds, planes, weather; Stratosphere: embedded, thin Ozone layer absorbs harmful UV radiation from the Sun; CFC's destroy O_3; Mesosphere: molecules break up into atoms; Ionosphere: atoms break up into charged ions and electrons from the solar UV, reflects radio waves making radio transmission possible; and and the Magnetosphere: The magnetic field of the Earth traps highly energetic charged particles, streaming from the Sun in the form of the Solar wind, into huge radiation belts (named Van Allen Radiation Belts) surrounding the Earth, thus protecting the Earth; Greenhouse Effect - visible radiation gets through re-radiated by the surface as heat in the IR, which is then absorbed and by heavy molecules in the atomosphere, mainly H_2O and other compounds such as CO_2, SO_2, i.e. energy from sunlight is retained; delicate balance; increase in pollutants such as CO_2,SO_2 may lead to `global warming'; the 'runaway' Greenhouse effect can lead to extremely hot temperatures, such as on Venus.
• Oct 14, Monday: Earth's geology - primordial icy matter from solar nebula and comets are most likely source of water. Structure of the Earth - crust, mantle, core; crust+upper mantle (lithosphere) "float" on the partially molten mantle; continents and oceans lie on the lithosphere, which is broken into 16 pieces called "plates". Movement of plates - Plate Tectonics - resoponsible for much geological activity such as volcanoes, formation of mountain ranges; plate boundaries - rift zones (e.g. mid-atlantic ridge), subduction zones (e.g. Japan oceanic trench), fault zones (e.g. San Andreas fault); "hot-spot" volcanoes (e.g. Hawaiin islands); magnetic field is due to convective motions of the molten iron core - electromagnet, the dynamo effect.
• Oct 16, Wednesday: The MOON - density 3.34 g/cc, therefore mostly rocky with little metallic iron core; surface has mainly two features: (i) Highlands - old (over 4 billion years), heavily cratered regions formed during early, heavy meteor bombardment, and (ii) Marias - younger (up to 3 billiion years) regions; Marias - "lunar seas" - formed with crater impact basins filling up with lava; no generally accepted theory of formation of moon; could be (i) accretion, (ii) fission (breakup), or (iii) capture, possibly combination of (i) and (ii) following large meteoroid impact on earth; number of craters indicates age: highly cratered regions are older, and lightly cratered regions are younger; lack of atmosphere leads to extreme temperatures, exposure to external material flying in, lack of surface evolution. MERCURY - surface features like the Moon, but high density, about 5.5 gm/cc, more metallic than the Earth with huge solid iron core (but little magnetic field, why?); no atmosphere, hence largest variation in day and night temperatures of any planet (though still less hot than Venus); Mercury rotates slowly; its "solar day" is twice as long as its `year' (sidereal orbital period around the Sun); Mercury takes 88 Earth days to revolve around the Sun, and 59 Earth days to rotate on its axis; two hot poles on the Equator; owing to its high eccentricity (0.26), its perihelion is 1.5 times closer to the Sun than aphelion, therefore receives 1.5 x 1.5 = 2.25 times more solar energy at perihelon (recall the inverse-square law of `brightness').
• Oct 18, Friday: VENUS - hottest planet overall due to "runaway" greenhouse effect; rotates very slowly and backwards; 90 times denser atmosphere than the Earth. The Vanera landers landed on the surface without a parachute!); atmosphere is 96% CO_2 (Mars' atmosphere is also 95% CO_2, but is 90 times lighter than Earth's); little free O_2; sulfuric acid clouds, absorb sunlight that causes fast "jet stream" winds up to 300-400 Kms/hr; little magnetic field due to slow rotation; although has molten iron core like the Earth. Large volcanic planes with "shield" volcanoes associated with hot spots; no plate tectonics; contrast and compare the greenhouse effect on the Earth and Venus. VIDEO: Http://Bit.ly/pradhanvenus
• Oct 21, Monday: MARS: Red planet due to iron oxide dust; eccentric orbit with e = 0.09; basic statistics: unlike Earth in mass and size, but with significant similarities (day, seasons, temperature); thin atmosphere due to low gravity and mostly CO_2 (95%) like Venus; robotic missions looked for 'life' but no sign (yet?); Polar caps of dry ice (frozen CO_2) and water ice underneath. Perihelion occurs during southern summers, which are hot but short; however, northern hemisphere is warmer with volcanic plains and huge shield volcanoes; southern hemisphere has a geology like the Moon with craters and marias; long ridges and canyons (e.g. Valles Marineris - 5000 Kms long!) are evidence of water flows billions of years ago. Martian dust storms are example of "anti-greenhouse" effect -- warm dusty layer absorbs sunlight and prevents it from reaching the colder surface, causing increased convection feeding the cycle; lessons for "nuclear winter" and extinction of dinosaurs; no sign of life at present (Viking lander experiments); terraforming may be possible; two small moons - Phobos and Deimos (about the size of the Columbus I-270 beltway).
• Oct 23, 25 Wednesday, Friday: JUPITER, Ch.9-11 -- largest planet; behaves like a "failed star" - insufficient mass to initiate nuclear fusion, but gravitationally producing energy by compression and expansion. Interior contains mainly H,He, like the Sun and all other Jovian planets; H_2 atmosphere and interior; H_2 in liquid and metallic form; intercomparison of Jovian planets; 2 subgroups: Jupiter and Saturn with metallic H2 interior, Uranus and Neptune much less massive and without metallic H2; temperature and pressure increase much more rapidly in Jupiter with depth than in Saturn; H_2 oceans about 40000-50000 Kms deep; due to high pressures H_2 molecules are tightly packed and electrons can move around like in metals; internal energy source due to self-gravity gives rise to vertical convection resulting in rising or falling material, or alternative bright or dark stripes, called "belts" or "zones". Convection due to fast rotation causes electric currents and a huge magnetic field, about 20000 times stronger than Earth's; rotation period about 10 hrs. Four Gallilean satellites: Io, Europa, Ganymede, and Callisto; Io and Europa are more rocky, rather than icy, in comparison with Ganymede and Callisto; Io has volcanic activity due to tides of Jupiter; Sulphur from volcanic activity is blown into Io's orbit and ionized by radiation field around Jupiter (ionized Suphur emission lines are observed). Europa and other galilean moon have icy crust and mantle, increasing with distance from Jupier; Europa has some Oxygen in a very thin atmosphere.
• Oct 28, Monday: Lecture via Carmenzoom; enter passcode 627291.
• Oct 30, Wednesday: PopQuiz3
• Nov 1, Friday: In-person, in-class, Mid-term Exam3 via carmen, NOT carmenzoom; covers material since Exam2.
• Study Guide Quiz 3. This is a partial study guide; follow the daily outline and lecture files for a complete list of topics.
• Nov 4, Monday: SATURN - second largest planet; contains smaller metallic mantle than Jupiter and consequently smaller magnetic field; density 0.69 g/cc, less than water; 18 moons; thousands of rings made up of icy-rocky particles; made up of material from moon that either did not form or broke up; "shepherded" by gravitational interaction with small moons in gaps between rings; ring particles are in Keplerian orbits within the Roche limit - tidal stability limit, about 2.5 times the planet's radius; particles in 'gravitational resonance' with the moons are ejected, those remaining in the rings are 'guided' by moons' gravity; Titan is the most interesting moon, only one with a real atmosphere, with about 1.6 times Earth's atomospheric pressure; Titan contains 80% Nitrogen, together with other gases including Oxygen (locked in ice), methane, ethane etc.; also contain organic C-H molecules; Titan is in a primordial state like Earth's in the first billion years; slow chemical evolution due to far colder temperatures; outer moons are heavily cratered, for example Mimas. Latest view of Saturn from Cassini: http://www.slate.com/blogs/bad_astronomy/2013/11/12/saturn_incredible_mosaic_of_the_ringed_wonder.html
• Nov 6, Wednesday: URANUS and NEPTUNE - Both discovered with telescope; Uranus discovered accidentally, but Neptune's existence was predicted mathematically. Voyager 2 used "Gravity slingshot" effect to explore all outer planets; Uranus and Neptune are "twins" in size and composition; bluish-green due to methane, which is the prime constituent in the atmosphere and mantle - not Hydrogen like Jupiter and Saturn since Uranus and Neptune are not massive enough and H escapes (however Helium is retained). Uranus is tilted at 98 degrees, i.e. rotational axis is in the oribital plane, therefore each pole is tilted towards the Sun for half the orbital period (84 yrs); faint rings of Uranus discovered by occultation of starlight; atmospheres of both Uranus and Neptune extend into the ring systems makeing them unstable; ring particles impact the moons with heavy cratering activity; Uranus's moon Miranda has a bizarre terrain and might have broken up and re-assembled; Neptune has a moon Triton in retrograde rotation, may have been captured; Neptune also has a great black spot like Jupiter's red spot. Triton has a very thin atmosphere and is denser than expected at this distance (2 g/cc), rather than icy like the outer Gallilean satellites, again indicating that it might have been captured.
• Nov 8, Friday: PLUTO and Kuiper Belt Objects. Pluto - Planetesimal, minor planet, the first of the Kuiper Belt Object (KBOs); discovered in 1930 after long search; WAS the smallest planet, only 0.0022 times the mass of the Earth; has the 'largest' satellite - Charon- relative to the size of the "planet"; Charon is about 8% of Pluto's mass (our Moon is about 1% of Earth's mass); Pluto-Charon form a 'double-planet' system, tidally locked by gravity - each faces the other; Surface T ~ 40 K.
• Nov 13, Wednesday: Debris of the solar system - Comets,Asteroids, eteoroids,Meteors,Meteorites; the ASTEROID BELT - rocky and metallic composition; families of asteroids with stray ones that might strike the Earth. METEORITES - small stony, irons, or stony-iron type objects; stony ones have organic material; composition similar to asteroids. COMETS - dusty ice balls about 1-10 kms; short-period comets (100's years) from the Kuiper Belt beyond the orbit of Pluto, such as Halley's comet with a period of 75-76 years; long-period comets (1000's of years or much longer) from the Oort Cloud; METEORS - icy particles like cometary material; burn up in the atmosphere like "falling stars".
• Nov 15, Friday: LIFE -- Definition, orgin, criteria; Physical definition --> DNA, self-reproducing molecule; CHON (C,H,O,N) elements make up building blocks of DNA which themselves are easy to form in the laboratory and found in interstellar space; Miller-Urey experiment; extraterrestrial candidates; intra-solar possiblities in Mars, Europa, Titan; Probability estimated by Drake equation; solar systems in the Milky Way; requirements for the star; requirements for the planet.
• Nov 18, Monday: Planetarium show at class time (Exoplanets) + assignment.
• Nov 20, Wednesday: Special lecture on the Sun by Prof. Sultana Nahar; Properties of the Sun, related to the material covered in class and stellar physics + Popquiz 4.
• Nov 22, Friday: Mid-term exam 4.
• Quiz 4 studyguide, and including material since the last mid-term exam 3, but not Prof. Nahar's lecture.
• Nov 25, Monday: Extra-solar planets or exoplanets; Jupiter-like, Earth-like, or in between; more than 5000 found, but recent discoveries imply that there should be billions! techniques for discovering exoplanets. The SUN - An introduction: H --> He fusion energy, sunspots, magnetic field, photosphere, corona, solar wind, flares, mass ejections, limb darkening; Solar interior -- fusion core, radiative zone, convection zone and currents, temperatures and densities.
• Nov 27-Dec. 1, Wednesday-Sunday, Thanksgiving break, no classes.
• Dec. 2, Monday: Origin of the solar system
• Dec. 4, Wednesday: No class, but office hours by appointment and via zoom.
• Dec, 12, Thursday: FINAL EXAM IN-PERSON IN-CLASS 10:00-11:45 AM on Carmen.

  Owing to possible last-minute changes, also check powerpoint files below AFTER lectures

  POWERPOINT LECTURE FILES

  Please note that this material is posted as an aid to, and not as a substitute for, class lectures. Any questions should be preferably addressed in class (not by email).

  Ignore lecture file 8 which repeats the information in file 7

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  Revised: Nov 24, 2024