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Elements of Astronomy and Cosmology Outline 1

Elements of Astronomy and Cosmology Outline 1

ELEMENTS OF AND OUTLINE 1. The Solar The Four Inner The Belt The Giant Planets The

2. The Neighborhood of the Terminology

3. The Early Twentieth Century Progress Recent Progress

4. Observation Ground-Based Telescopes -Based Telescopes Exploration of Space 1 – The Solar System The Solar System

- 4.6 billion old

- formation lasted 100s millions years

- Four rocky planets ( , and )

- Four gas giants (, , and )

Figure 2-2: Schematics of the Solar System The Solar System

- ()

- Kuiper belt ()

Figure 2-3: Circular of the planets in the system The

- Contains mostly and - Sustained - ~ 15 million K

- Elements up to Fe form

- Is some 5 old - Will last another 5 billion years

Figure 2-4: Photo of the sun showing highly textured plasma, dark , bright active regions, coronal ejections at the and the sun’s . The Sun

- Dynamo effect

- Magnetic storms

- 11- cycle

- Solar (energetic )

Figure 2-5: Close up of dark spots on the sun surface Probe Sent to Observe the Sun

- Distance Sun-Earth = 1 AU

- 1 AU = 150 million km

- from the Sun takes 8 minutes to reach Earth

- The takes 4 days to reach Earth

Figure 5-11: used to monitor the sun Venus - Brightest planet at

- 0.7 AU from the Sun

- Hot at 400 oC

- Remnant of atmosphere

- Rotates in the opposite direction

- 1 Venus year = 225 earth days - 1 Venus = 243 earth days

Figure 2-6: photo of Venus (taken by the ) showing a mountainous terrain The Earth Core

No Halfnium Core-mantle separation Tungsten Radioactive decay complete

Halfnium Tungsten Radioactive decay not complete Halfnium


Figure 2-9: The Halfnium-Tungsten decay and its implication that the core-mantle separation happened less than 45 million years after the formation of Earth The Earth Interior

35 700 crust - Mantle formed of (rocks)

upper mantle - Core formed of metals (, nickel) lower mantle 2885 - Hot temperatures in core (4-5,000 oC)

outer core - Lower temps in mantle (> 600 oC) 5155 inner core 6371 - Top crust (ambient to 600 oC) Depth in km

Figure 2-10: Schematics showing the Earth’s inner solid core, outer liquid core, mantle and thin curst. The

- As old as Earth

- manned missions brought rocks back

- The Grail mission

Figure 2-7: Photo of the lunar surface showing many craters Mars

- missions (1970s)

- Rover missions (10 years)

- Thin atmosphere of CO2

- Presence of ice at the

Figure 2-11: One of the Mars rovers Mars

- Lack of

- Exposed to solar wind

- Some chemical analysis was performed

- was detected. Is it of a geological or biological origin?

Figure 2-14: The Mars Lab The Asteroid Belt

- Spacecrafts do not travel in straight lines

- They use the of planets

- and are large

- The craft just reached Ceres

Figure 2-15: The Dawn craft sent to Asteroid Ceres Jupiter

- Contains hydrogen on the outside and helium on the inside

- Has 318 Earth’s mass

- It’s a gravitational giant

- spacecraft (1989-2003)

Figure 2-16: The Galileo spacecraft that was sent to Jupiter Jupiter

- Has distinctive bands ()

- Has 67 including , , ,

Figure 2-17: Photo of Planet Jupiter with its distinctive cloud bands. Jupiter

- The spacecraft was launched in 2011

- Arrived in 2015 for detailed studies of Jupiter and some of its moons

Figure 2-24: The Juno spacecraft is on its way to Jupiter Jupiter

- Cassini spacecraft mission

- Moon Io contains volcanoes

- Ganymede and Callisto contain cores containing rocks and metals

Figure 2-19: Close up of Jupiter and its moon Io. A eruption can be seen on Io Saturn

- Cassini spacecraft explored Saturn (1997-2017)

- Landed probe on

Figure 2-20: The Cassini spacecraft Saturn

- Saturn has rings of rocks and ice

- Saturn has 62 moons such as and Titan

- Titan has methane atmosphere and methane lakes

Figure 2-21: Photo of Planet Saturn with its rings and of a few of its (moons) passing in front of it (four on the left side and a larger one at the top). and 2

- Were launched in 1977 - reached Jupiter in 1979, Saturn in 1981, Uranus in 1986 and Neptune in 1989 - Is crossing the Kuiper Belt which extends to 150 AU - Comets come from the Kuiper Belt - Halley (every 75 years) - Sun’s gravity dies out at 125,000 AU = 2 light years

Figure 2-25: One of the Voyager spacecrafts Spacecrafts – Solar System Table 2-1: Spacecrafts sent to objects of the Solar System Spacecraft Year Planet Mission

Mariner 2 1962 Venus Flyby and 9 1965 and 1971 19974 Mercury Flyby and 2 1976 Mars , then landing and 11 1973 and 1974 Jupiter, Saturn Flyby

Apollo Missions 1969-1972 Moon Obit, man landing, returned rocks Voyager 1 and 2 1977 still going, presently Jupiter, Saturn, Uranus, Flyby located at over 100 AU Neptune, etc

Galileo 1989 Jupiter and its moons Flyby, orbit, launched probes Cassini 1997-2000s Saturn and its moons Flyby, orbit, launched probes 1990 Sun Study solar wind, etc Pathfinder, Global and 2000s Mars Oribit, landing, surveying Survey and Rover for years Missions

Stardust 1999 Comet Flyby, return 2 – The Milky Way Galaxy The Milky-Way Galaxy

Outer arm Sagittarius arm arm - Sun - Sun is at 26,000 light years from galaxy center spur - Galactic revolution = 120 million years

Figure 3-1: Representation of the Milky Way galaxy as viewed in its disk plane. The dot represents the Sun’s location. The Milky-Way Galaxy

Halo Sun Globular clusters - Closest star to the Sun is Centauri at 4.2 light years

Disk Galaxy center - Sagittarius is Central bulge at the galaxy center

- Galaxy center is site of hole

Figure 3-2: Schematics of the profile view of the Milky Way galaxy. It extends to 100,000 light years, has a thickness of some 1,000s and contains hundreds of billions of . Well Known

The Little Dipper The Star

Ursa Major The Big

Figure 3-3: The and Ursa Minor constellations in the Milky Way galaxy have the shape of a with handle. Polaris is also called the North Star since it indicates the north. The Space

- The Kepler mission (2009-2013)

Figure 3-4: The mounted on Delta after launch The Kepler Space Telescope

- Sent to monitor 150,000 stars in the Milky Way

- From Earth’s orbit

- Used ~ 1 m telescope and high-res. CCD cameras

Figure 3-5: The Kepler Space Telescope after separation from its launch rocket Exoplanets

- Methods for detecting exoplanets: tugging, imaging and transiting

- Kepler detected hundreds of exoplanets

Figure 3-6: Photo of an transiting in front of its star Exoplanets

- Hundreds of exoplanets have been identified by the transiting method

- used to identify water and gases essential to

- Zone where water is liquid (habitable or Goldilock zone)

Figure 3-7: Data showing dimming of light from a star taken by the Kepler Space Telescope. This indicates the presence of an exoplanet Star Terminology

- Stars form from giant of gas and dust.

- Gravitational compression raises the . Starts nuclear fusion converting hydrogen into helium that sinks deep.

- When hydrogen runs out, the star collapses . Fusion of helium into starts, expands into a .

- When helium runs out, the star collapses into a dwarf (planet ).

- Very large stars finish their life cycle in supernovae .

- leaves a star.

- are small pulsating neutron stars. 3 – The Early Universe Early Telescopes

- 1.5 m telescope

- Reflection instead of refractive

- 1920s

- Hubble discovered

- Doppler shifts allow precise of

Figure 4-1: The telescope on Mount Wilson Space-Based Telescope

- Above the atmospheric blur

- Specialized over narrow window of

Figure 4-2: The Wilkinson Anisotropic Probe (WMAP) Cosmic Microwave

- In the 1960s Penzias and Wilson discovered the cosmic microwave background

- Temperature of the universe around 2.72 K

- left over from the

- Big Band occurred 13.7 billion years ago

Figure 4-3: image showing the ever slight changes of the temperature of the universe (relative changes of 10-4). This is the radiation remaining from the Big Bang measured with WMAP. Anti Gravity and Dark

- is a form of anti gravity

- Dark energy makes the universe expand faster

- Accounts for some 68 % of the universe

- Only 5 % of the universe density can be observed

Universe is expanding faster – dark hypothesis Gravity and

- Dark matter is an invisible form of gravity

- Can be observed only through its gravitational effects

- Accounts for some 27 % of the universe density

- Is still not understood

- Weakly Interacting Massive (WIMP)

- Einstein’s concept of gravity

Figure 4-4: Einstein’s concept of gravity as a trough in the space/ fabric located at a heavy object. Attracted objects fall into the trough. Black Holes

- Large at the center of every galaxy

- There are many black holes in each galaxy

- Devour everything close

- Do not emit light

Figure 4-5: Representation of a black hole Black Holes

- Gravitational effect of black hole on the of stars

- of huge star produces black hole

- Black holes are not understood

Figure 4-6: Hairpin turn of stars around a black hole is evidence of the presence of the black hole 4 – Observation Telescopes Ground-Based Optical Telescopes

Figure 5-1: The Keck telescopes on in Hawaii Ground-Based Infrared Telescopes

Figure 5-2: The Sloan Digital Survey telescope in New Ground-Based Infrared Telescopes

Figure 5-3: Fiber used in the telescope Ground-Based Radio Telescopes

- 305 meter radio dish

- Observation of distant and galaxies

Figure 5-4: The at the Aricebo in Puerto Rico The

- Was deployed in 1990

- Continuous observation of space in Visible, IR and UV

- Observed birth of galaxies, galaxy clusters, binary stars, supernovae, dwarf stars, etc

- Without atmospheric blurring

Figure 5-5: The Hubble space telescope being launched from the The Hubble Space Telescope

- Could no longer be serviced since the end of the US

- Is approaching its end

- Will be replaced by the JWST

Figure 5-6: The Hubble space telescope orbiting around Earth The James Web Space Telescope

- Will replace Hubble

- To be launch in 2018

- Will follow elliptical orbit at 1.5 million km (0.01 AU)

- Will study the formation of the very first galaxies

- Will on the imaging of exoplanets and identifying habitable ones

Figure 5-7: Rendering of the James Web Space Telescope Ray Telescope

- Pulsars emit gamma rays

- Supernovae explosions emit gamma rays

- Insight into dark matter and black holes

Figure 5-8: The SWIFT explorer New Telescopes

Ground-Based Telescopes

- Correct for atmospheric blurring using vertical laser.

- 30 meter Telescope planned in Mauna Kea, Hawaii. Will incorporate corrective optics to adjust for atmospheric blur. Over the next 10 years.

- 40 meter Extremely Large Telescope () is being built in Chile. Completion planned for 2022.

- Square Kilometer Array radio telescope located in and but working together (3,000 km apart).

Space-Based Telescopes

- James Web Space Telescope Hubble Images

Figure 5-9: Infrared picture of the Milky Way galaxy Hubble Images

Figure 5-10: Infrared photos of colliding galaxies Hubble Images

Figure 5-12: Photo of a Hubble Images

Figure 5-13: A star nursery Hubble Images

Figure 5-14: The Butterfly Nebula Hubble Images

Figure 5-15: The Hubble Images

- emits energy

- Black hole at the center

- Large/small black holes

- Emits x-rays, visible, IR, etc

Figure 5-16: Invisible jets of energy emitted from the center of a spiral galaxy Exploration of Space

Since the US Space Shuttle program was stopped in 2011, the International (Russia) has been the only permanent observation platform in orbit around Earth. Its orbit takes 90 minutes.

NASA is working on the Crew Exploration Vehicle. Phase One will take it into low Earth orbit. Phase Two will be to send a crew to the Moon. Phase Three will be a long trip (several ) stay at the Moon. Phase Four will be a flyby of Mars Phase Five will be landing a crew on Mars sometime after 2030. Summary

TREMENDOUS PROGRESS IN ASTRONOMY Solar system, Milky Way, other galaxies Observation platforms (Hubble, Kepler, James Web) Exoplanets, habitable zone Spacecrafts (Galileo, Cassini, Juno)

OUTSTANDING MYSTERIES Dark energy (anti-gravity) makes the universe expand faster, 68 % Dark matter (invisible) is a form of gravity, 27 % Black Holes in the Lab (Tevatron machine)