ASTROPHYSICS UNIVERSE

Know locations The Solar System

The Sun  Mass: 1.99 x kg  Radius:6.96 x 10 8 m  Surface temperature: 5800 K  Mass: 1.99 x kg  Radius:6.96 x 10 8 m  Surface temperature: 5800 K

PlanetPictureDistance to the Sun (km) Radius (km)Orbital period around its axis Orbital period Surface day temp (ºC) Density (water=1) Satellites Mercury58 million4 878 km59 days88 days1675,430 Venus108 million km-243 days225 days4645,240 Earth149,6 million km23, 93 h365,2 days155,521 Mars228 million6 794 km24h 37min687 days-653,042 Jupiter778 million km9h 50min 30s12 years-1101,32+63 Saturn1 427 million km10h 14min29,5 years-1400,69+56 Uranus2 870 million km16h 18min84 years-1951,2727 Neptune4 497 million km15h 48min164 years-2001,7713 Pluto5 900 million2 400 km6 days248 years Planets Data

Mercury and Venus

Earth and Moon Mariner 10

Solar System Formation 1.Giant cloud of molecular Hydrogen gathered together by gravity. 2.Clumps of matter collapsed and heated up. 3.Gas disc of young, spinning star evolved planets (Estimated 4.6x10 9 years ago), asteroids & comets. 4.High temp. close to Sun allowed only the compounds with high condensation temperatures to remain solid – hence forming 4 terrestrial planets. (Mercury, Venus, Earth & Mars) 5.Further out, “gas giants” or “jovian,” planets form around cores of rock, metal and ice.

Earth and Moon

Mars Spirit Rover: Mars’ West Valley

Mars

Viking: Martian Face ESA’s Mars Express: Cydonia Region

Know location Asteroid Belt Ceres (480km): it was the first asteroid to be seen. Now it’s a dwarf planet. Mathilde (52km) Eros (13x13x33km)

Jupiter Jupiter and its moons: Io, Europa, Ganymede and Callisto Approximate size comparison of Earth and Jupiter

Saturn A rough comparison of the sizes of Saturn and Earth

Uranus Size comparison of Earth and Uranus

Neptune Size comparison of Neptune and Earth.

Other Solar System Objects Kuiper belt - Beyond Neptune Source of many dwarf planets, asteroids and short- period comets. Larger than the asteroid belt. Asteroid belt – Between Mars & Jupiter Possibly formed from a terrestrial planet that was destroyed. Rocky objects with irregular shapes for those whose size < 300Km because they couldn’t form a sphere. Some could be called minor planets (Ceres d=10 6 m). Comets – Irregularly shaped bodies of ice & rock Very elliptical orbits. Comet tail: points away from sun, is vaporized gases.

Star Groups Binary Stars –Two stars around a center of mass Stellar Cluster Close enough to be held together by gravity. Few dozen to millions of stars. All formed at the same time. Open Cluster: i.e. Pleides (≈500 stars) Up to several 100 stars Younger than 10 Billion years thus may still have some dust & gas In our galaxy so in a single plane. Globular Cluster Many more stars & older than 11 billion yrs. Roughly spherical in shape – little or no dust or gas. Just outside Milky Way in “galactic halo.”

Galaxies A galaxy is a collection of a very large number of stars mutually attracting each other through the gravitational force and staying together. The number of stars varies between a few million and hundreds of billions. There approximately 100 billion galaxies in the observable universe. There are three types of galaxies: - Spiral (Milky Way) - Elliptical (M49) - Irregular (Magellanic Clouds)

Spiral Galaxies Spiral galaxies consist of a rotating disk of stars and interstellar medium, along with a central bulge of generally older stars. Extending outward from the bulge are relatively bright arms. Milky Way

Spiral Galaxies Andromeda

Spiral Galaxies Sombrero Galaxy

Elliptical Galaxies M49 Elliptical cross-section and no spiral arms. They range in shape from nearly spherical to highly flattened ellipsoids and in size from hundreds of millions to over one trillion stars. In the outer regions, many stars are grouped into globular clusters. ESO 325-G004

Irregular Galaxies Irregular galaxies have no specific structure. The Large and Small Magellanic Clouds, the nearest galaxies, are an example of irregular galaxies. Small Magellanic Cloud Hoag's Object, a ring galaxy.

Constellations A group of stars in a recognizable pattern that appear to be near each other in space. Orion

Polaris

Nebulae Nebula is an interstellar cloud of dust, hydrogen gas and plasma. It is the first stage of a star's cycle but it can also refer to the remains of a dying star (planetary nebula). Originally nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy was referred to as the Andromeda Nebula before galaxies were discovered by Edwin Hubble). Nebulae often form star-forming regions, such as in the Eagle Nebula.

Nebulae Eagle Nebula and the Cone nebula: star-forming regions

Cat’s Eye Nebula Planetary nebulae are nebulae that form from the gaseous shells that are ejected from low-mass giant stars when they transform into white dwarfs.

Eskimo nebula

???  What is the difference between a stellar cluster and a galaxy?  How do constellations differ from stellar clusters or galaxies?  What are the two ways nebulae can be formed?  1. Nuclei captured electrons electrostatically forming dust & gas clouds of Hydrogen.  2. Matter ejected from a super novae.  What is the difference between a stellar cluster and a galaxy?  How do constellations differ from stellar clusters or galaxies?  What are the two ways nebulae can be formed?  1. Nuclei captured electrons electrostatically forming dust & gas clouds of Hydrogen.  2. Matter ejected from a super novae.

Supernovas Eta Carinae Crab Nebula

Astronomical Distances  1 ly 9.46x10 15 m light year: Distance light can go in a year traveling at 3E8ms -1  1 AU 1.50x10 11 m Astronomical Unit: Average distance between Earth and Sun.  1 pc3.26 ly= 3.09x10 16 m parsec: most commonly used system of distance in astrophysics.  1 ly 9.46x10 15 m light year: Distance light can go in a year traveling at 3E8ms -1  1 AU 1.50x10 11 m Astronomical Unit: Average distance between Earth and Sun.  1 pc3.26 ly= 3.09x10 16 m parsec: most commonly used system of distance in astrophysics.

???  How many minutes does it take light from the sun to reach the earth?  about 8 minutes  Distances between stars in a galaxy are often given in kpc. What does this stand for?  Kiloparsecs  How might you represent distances between galaxies?  Mpc or Gpc  How many minutes does it take light from the sun to reach the earth?  about 8 minutes  Distances between stars in a galaxy are often given in kpc. What does this stand for?  Kiloparsecs  How might you represent distances between galaxies?  Mpc or Gpc