Origin of our Universe: Life of Stars

A star's color tells us how hot or cold it is. STARS: a self-luminous celestial body of gas of which produces energy by means of nuclear fusion reactions. A star's color tells us how hot or cold it is. Red stars are not as hot as blue stars. Our sun is a yellow star. That makes it one of the cooler stars.

Stars Brightness A stars brightness is dependent on 3 factors Temperature Size Distance from the Earth

Our Sun 5 billion year old small star (should last 5 more) Composed of 75% hydrogen and 25% helium Elements in plasma phase (hotter state than gas) Energy comes from a Nuclear Fusion Reaction

Nuclear Fusion Reaction Joining two hydrogen to create helium Releases large amount of energy Fusion = join Fission = split Sun: joining (fusion) things to release energy Power Plants: splitting (fission) things to release energy

There is obviously more to the Sun then “burning ball of gas”

Core – centre and site of nuclear fusion Outside Layers of the Sun: Inside Core – centre and site of nuclear fusion Outside Photosphere – cooler surface (5500 oC) sunspots, surface storms – the part we “see” Chromosphere – inner atmosphere small solar explosions (flares), large (prominences) Corona – outer atmosphere (1 million oC) charged gas particles blow outward (solar winds)

“Life Cycle” of a Star Birth: Stars born out of Nebulae Nebula – huge clouds of dust and gas Youth – Middle Age: Gravity collapses material into a star that begins to release energy as a main sequence (MS) star Scientists categorize MS stars according to mass: Small - last longer (billions of years) Large - brighter but short-lived (few million yrs)

Attracted by gravity; matter clusters together Nebula 99% hydrogen and helium 1% iron, rock and ice Attracted by gravity; matter clusters together

Actually nebulae captured by NASA space telescopes

We can’t see most Red Dwarf stars – their light is too weak Small MS star – Red Dwarf Very cool temperatures of their outer gases Death: Forms a cool, dim star called a White Dwarf Fades out until it no longer emits light energy We can’t see most Red Dwarf stars – their light is too weak

Medium MS star – like the Sun Separated into small-med and large-med Death: Runs out of elements for fusion reaction Collapses then swells to produce a Red Giant small-med eventually fades out as white dwarf large-med explodes as a Supernova leaving behind a Neutron star “Pulsar” neutron star

Extreme energy produced for a short period Large MS star Extreme energy produced for a short period Fuses heavier elements (iron) after lighter ones Death: Collapses then swells to a Red Supergiant Gravity collapses the largest into a Black Hole Stars are in balance: nuclear fusion explodes outwards, large gravitational force collapses inwards When the reactor runs out of elements to fuse, gravity wins and the star collapses and (sometimes) explodes

There is still more to this puzzle, but…this is close enough Birth: Nebulae Smallest main sequence (MS) star Largest Medium Red Dwarf Red Giant Red Supergiant Supernova Death: White Dwarf Neutron star Black Hole There is still more to this puzzle, but…this is close enough

What do you notice?

Galaxies Huge collections of gas, dust and billions of stars and planets (collected by gravity) Constantly in motion Many shapes: spiral, elliptical, and irregular

Contains 400 billion stars Milky Way Galaxy Contains 400 billion stars Disc-shaped, with spiral arms – spiral galaxy We are on one of the arms Has a thicker Central Bulge Rotates around the bulge New evidence suggests the “central bulge” is actually a SUPER-MASSIVE BLACK HOLE!

CAN YOU ANSWER THESE QUESTIONS? S1-4-08: How do star create energy? What objects make up our solar system and Universe? Vocabulary & Concepts  Core Fusion Nebula Supernova Black hole Galaxy

Origin of our Universe: Planets and Things

OUTCOME QUESTION(S): S1-4-08: Vocabulary & Concepts What objects make up our solar system and Universe? Vocabulary & Concepts  Asteroid belt Kuiper belt Moon Asteroid Meteoroid Meteor Meteorite Comet

Jupiter, Saturn, Uranus and Neptune Formation of our Solar System All matter recycled from past supernova explosions Outer region of nebula: Gases (far from forming Sun) begin to cool Cluster together and condense Forming the Gas Giants: Jupiter, Saturn, Uranus and Neptune Gas Giants appear to lack solid surfaces, but the gases may become liquid or solid deeper towards their dense core

Mercury, Venus, Earth and Mars Inner region of nebula: Gases in the inner region too hot to condense Chunks of iron and rock collide and stick together Forming Terrestrial Planets: Mercury, Venus, Earth and Mars “Terrestrial” planets have a surface of rock, iron and hard elements through to the molten core

Terrestrial planets

It rotates so slowly that its “year” is less than 2 “days” long Mercury Closest to the Sun Receives sunlight 10x brighter than Earth Day temperatures over 400°C No atmosphere - so night temp fall to -180°C Day (rotation) – 59 Earth days Year (revolution) – 88 Earth days It rotates so slowly that its “year” is less than 2 “days” long

Venus 3rd brightest object in the sky CO2 atmosphere traps heat (+ 465°C) Many volcanoes eject tonnes of sulphur Clouds of sulphuric acid makes acid rain Day (rotation) – 243 Earth days Year (revolution) – 225 Earth days Sun and Moon are brightest objects Its “year” is shorter than its “day”

Earth Atmosphere (N2, O2, H2O) stabilizes temperature Ranges from -85oC to +65oC Liquid water covers about 70% of surface Generally stable – some volcanoes, earthquakes Day (rotation) – 1 Earth days Year (revolution) – 365 1/4 Earth days Distance from the Sun is most responsible for the factors that contribute to Earth’s ability to sustain life

Mars Bright red - iron oxide dirt makes it reddish Most studied planet (no signs of life… yet ) Of all planets, Mars is most like Earth Surface temp ranges from -120oC to +30oC Day (rotation) – 1 Earth day Year (revolution) – 687 Earth days Although it is dry and barren now, scientists have evidence that may point to past glaciers and liquid water

An Asteroid Belt separates the Terrestrial planets from the Gas Giants – maybe remains of a totally smashed older planet

The Gas Giants

Jupiter Largest of the planets (11x bigger than Earth). Has 63 moons (2006) Great Red Spot is a continuous hurricane Temp around -160oC Day (rotation) – 10 Earth hours Year (revolution) – 11.9 Earth years The coloured bands are gas clouds being streaked over the surface as it rotates quickly

Saturn 2nd largest of the planets 3 moons and a shadow in this picture 2nd largest of the planets Least dense – may not have a solid core Rings stretch from Earth to Moon 60 moons and 1000 rings (could be crushed moon) Day (rotation) – 11 Earth hours Year (revolution) – 29.5 Earth years Notice the coloured bands on the surface here too

It is now pronounced “ur-an-is” not “ur-anus” Rotates on its side Extremely cold -210oC Has several narrow, dark rings Has 27 moons Day (rotation) – 17 Earth hours Year (revolution) – 84 Earth years It is now pronounced “ur-an-is” not “ur-anus”

Neptune has some faint rings too, and 20 moons Only discovered because its gravity “tugs” on Uranus’s orbit causing changes Blue and white – methane in atmosphere The Great Dark Spot is a gigantic storm Extremely cold -220oC Day (rotation) – 16 Earth hours Year (revolution) – 165 Earth years Neptune has some faint rings too, and 20 moons

Pluto was reclassified as a dwarf planet in 2006 Kuiper Belt and the Oort Cloud Contain thousands of icy and rocky objects Kuiper Belt – Neptune to about 30 to 55 AU Oort Cloud – from 5000 AU to 100000 AU Pluto and Eris are the best known dwarf planets found in Kuiper belt Pluto was reclassified as a dwarf planet in 2006

Moon: Large natural object (rock/metal) that revolves around a planet – also called a satellite. Humans have visited the moon’s surface six times between 1969 and 1972. Planet (2006) Known moons Mercury Venus Earth 1 Mars 2 Jupiter 63 Saturn 60 Uranus 27 Neptune 13 Pluto 3  

Asteroid belt in large gap from Mars – Jupiter Asteroid: Chunk of rock/metal that orbits the Sun but too small to be considered a planet. Asteroid belt in large gap from Mars – Jupiter Largest is 1000 Km in diameter Asteroid that crosses Earth’s path called a Trojan Asteroids can get bumped and smashed into a new orbit and sometimes that orbit can get “close” enough to be pulled in by Earth’s gravity.

Meteoroid that completely burns up - meteor Meteoroid: lump of rock that is trapped by Earth’s gravity and pulled into the atmosphere. Falling meteoroids bump into air molecules heating up (friction) until the air glows – and the meteoroid burns up and breaks apart. Meteoroid that completely burns up - meteor producing a streak of light - “shooting star” The only difference between meteoroid and asteroid is that a meteoroid is random and an asteroid orbits the Sun

Meteorite impact crater in Arizona Meteorite: fragment of a meteoroid that doesn’t burn up and strikes the Earth (space rock). Large meteorite collisions make craters Westhawk Lake is a crater Meteorite impact crater in Arizona

Halley’s comet: last seen in 1986 it has a orbit period of 76 years Comet: chuck of ice/dust that orbits the Sun. Most originate from the Oort cloud Tail: passing by Sun heats trailing gas and debris then blown out by solar wind - millions of km long Some have regular periods of revolution Halley’s comet: last seen in 1986 it has a orbit period of 76 years

CAN YOU ANSWER THESE QUESTIONS? S1-4-08: What objects make up our solar system and Universe? Vocabulary & Concepts  Asteroid belt Kuiper belt Moon Asteroid Meteoroid Meteor Meteorite Comet