28-Aug-17. A Tour of Our Solar System and Beyond. The Sun

Transcription

1 A Tour of Our Solar System and Beyond The Sun diameter = 1,390,000 km = 864,000 mi >99.8% of the mass of the entire solar system surface temperature 5800 C 600 x 10 6 tons H -> 596 x 10 6 tons He per second But where does it go?... E = mc 2 About 2 mm in diameter on the "auditorium scale" 1

2 The Terrestrial or Inner Planets: Mercury diameter = 4880 km distance from Sun = 57.9 x 10 6 km Moon-like, with no wind, no rain, no life, no significant atmosphere more being learned from Messenger spacecraft surface temperature 425 C (797 F) day, -150 C (-240 F) night 7 microns on "auditorium scale", about 8.3 cm from Sun The Terrestrial or Inner Planets: Venus diameter = 12,100 km distance from Sun = x 10 6 km very dense atmosphere of carbon dioxide with sulfuric acid clouds and rain 450 C (850 F) day and night 17 microns on "auditorium scale", about 15.5 cm from Sun The Terrestrial or Inner Planets: Earth diameter = 12,760 km distance from Sun = x 10 6 km oxygen-containing atmosphere due to biological activity moderate greenhouse effect liquid H 2 O 1 moon 18 microns on "auditorium scale", about 21.5 cm from Sun 2

3 "Earth's City Lights" from Goddard Space Flight Center at The Terrestrial or Inner Planets: Mars diameter = 6,790 km distance from Sun = x 10 6 km CO 2 atmosphere, low pressure, very cold Once had liquid H 2 O and possibly life Curiosity rover investigates that possibility extinct volcanoes 2 moons (probably captured asteroids) 10 microns on "auditorium scale", about 33 cm from Sun Asteroids rocky diameter < 1000 km Irregular shape millions of km separate them left over from formation of solar system some danger of impacts to us 3

4 The Jovian or Outer Planets: Jupiter diameter = 143,000 km distance from Sun = x 10 6 km Gas giant with "rocky" core deep inside Massive pressures, high winds, gargantuan storms in H/He atmosphere Rings Many moons One of them, Europa, has a water ocean under its icy rind Is there life in that subsurface ocean? 0.2 mm on "auditorium scale", about 1.1 m from Sun The Jovian or Outer Planets: Saturn diameter = 120,000 km distance from Sun = 1427 x 10 6 km Gas giant with rocky core deep inside Rings Many moons Titan: bigger than Mercury, thick atmosphere, subsurface water ocean Enceladus: geysers from a subsurface water ocean Life again? 0.17 mm on "auditorium scale", about 2 m from Sun The Jovian or Outer Planets: Uranus diameter = 52,000 km distance from Sun = 2870 x 10 6 km Less proportion H and He than Jupiter and Saturn, more ices, so called ice giant Rotates on side Rings Many moons mm on "auditorium scale", about 4.1 m from Sun 4

5 The Jovian or Outer Planets: Neptune diameter = 48,400 km distance from Sun = 4497 x 10 6 km Similar to Uranus Rings Many moons Triton: orbits in opposite direction of Neptune's rotation suggests it was captured 0.07 mm on "auditorium scale", about 6.5 m from Sun No longer a planet now a dwarf planet: Pluto diameter = 2,320 km distance from Sun = 5900 x 10 6 km Rock and ice Orbit elongated and tilted Sometimes closer to Sun than Neptune At least 5 moons Charon, Nix, Hydra, P4, P5 Pluto is more like a giant comet-like Kuiper belt object than like the other planets So it is now classified as a dwarf planet 3 microns on "auditorium scale", about 8.5 m from Sun What are planets? (International Astronomical Union) A planet is a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and has cleared the neighbourhood around its orbit. The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. A "dwarf planet" is a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, has not cleared the neighbourhood around its orbit, and is not a satellite. Currently, the dwarf planets are Ceres, Pluto, Haumea, Makemake, and Eris (previously "Xena"). All other objects, except satellites, orbiting the Sun shall be referred to collectively as small solar system bodies". These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies. 5

6 Comets the most distant solar system bodies a trillion of them ice and dust Kuiper belt - Pluto-like giant comets as well as smaller ones Oort cloud - very large, maybe 1 ly radius, which on "auditorium scale" is about from UNF to Regency Square Comet 67P/Churyumov-Gerasimenko Imaged by Rosetta on 3 Aug 2014 distance = 285 km Beyond the Solar System Interstellar space The nearest star is the Sun But beyond the solar system the nearest is Proxima Centauri 4.2 ly away on "auditorium scale", this is 57 km, about the distance from UNF to St Augustine Proxima Centauri is part of the star system Alpha Centauri, which is part of the constellation Centaurus An image of Centaurus follows 6

7 How should you interpret images of the night sky like this one? For example, some of the stars are bigger than others So can you learn the size of stars from images like this? NO! The size in an image depends on brightness Stars are really the size of points On the auditorium scale, the nearest star is in St Augustine Think of it as looking at a bb a bright one in St Augustine! Can you learn how close stars are to each other? NO! Stars that are close in the sky may be far apart: Alpha Centauri 4.4 ly Beta Centauri ly Can you learn how close stars are to you? NO! Closer stars are not always brighter: Gamma Centauri ly Beta Centauri ly 7

8 Can you see planets? NO! Planets are very small and dim compared to stars even so...more than 3500 extrasolar planets have been found! The Extrasolar Planets Encyclopedia The Milky Way Our Galactic Home From Our Sun is located in the Orion Arm of the Milky Way about 28,000 light years from the center on the auditorium scale, that s about the distance from the Earth to the Moon The Milky Way Our Galactic Home From The Milky Way galaxy contains about 100 x 10 9 stars 8

9 The Milky Way Our Galactic Home From The Milky Way galaxy contains about 100 x 10 9 stars In the total observable universe, there are that many galaxies The Milky Way Our Galactic Home From The Milky Way galaxy contains about 100 x 10 9 stars In the total observable universe, there are that many galaxies So there are 100 x 10 9 x 100 x 10 9 = stars The Milky Way Our Galactic Home From The Milky Way galaxy contains about 100 x 10 9 stars In the total observable universe, there are that many galaxies So there are 100 x 10 9 x 100 x 10 9 = stars more than all the grains of sand on all the beaches on Earth! 9

10 Beyond the Milky Way The Milky Way is one of 3 dozen or so galaxies comprising the Local Group Beyond the Milky Way One of these is the Andromeda Galaxy, M31 Beyond the Milky Way The Andromeda Galaxy, M million light-years away 10

11 Beyond the Milky Way The Andromeda Galaxy, M million light-years away to the orbit of Venus on the auditorium scale 100,000 light-years across Beyond the Milky Way It s interesting to think about what we see when we look at this galaxy The Andromeda Galaxy, M million light-years away to the orbit of Venus on the auditorium scale 100,000 light-years across 2X the diameter of the Moon s orbit Beyond the Local Group The Hubble Deep Field 11

12 In the sky, this image spans about the same width as a dime viewed at 75 feet In the sky, this image spans about the same width as a dime viewed at 75 feet It contains at least 1,500 galaxies This more recent image of about the same amount of sky as the HDF was made with a longer exposure 12

13 This more recent image of about the same amount of sky as the HDF was made with a longer exposure It contains 10,000 galaxies This more recent image of about the same amount of sky as the HDF was made with a longer exposure It contains 10,000 galaxies Multiplying this number of galaxies by the number of HUDFs it would take to cover the entire sky is where the 100 billion galaxies in the observable universe comes from This is a 2 slice of the sky from an Australian observatory It shows the location of galaxies within the slice They lie on filaments that extend throughout the universe The edge on auditorium scale is 6 times farther from the Sun than Neptune 13

14 This tour should have given you a better sense of our place in space Now let s get a sense of our place in time with The Cosmic Calendar 14