We can use space exploration to learn about stars, nebulae, and galaxies outside our solar system

Learning about Space Our current understanding of the solar system has changed and improved with improved technologies Theories are based on evidence that are collected remotely

Early ideas years ago, you would have been told that things never change in space New evidence has caused scientists to rethink existing theories. Between 1918 and 1929 more powerful telescopes were developed and more celestial bodies were seen

Edwin Hubble: His contribution Edwin Hubble: The first astronomer to identify other galaxies besides the milky way. Galaxy: a collection of stars, planets, gas and dust held together by gravity He estimated the distance from Earth to 46 galaxies He noticed that all of the galaxies he was observing were moving away from each other He proposed that the universe is expanding in all direction Universe: The huge space which contains all of the matter and energy in existence.

Why did Hubble think the Universe was Expanding? Hubble used Red Shift analysis, using spectroscopy, to explain how the universe is expanding The light that leaves a distant galaxy travels an enormous distance through space before reaching a telescope. When a galaxy first emitted its electromagnetic waves they were not red shifted (or made longer) Only as space expanded did it cause the waves to lengthen and become red shifted

Edwin Hubble… This shows that the light’s wavelengths are becoming longer It indicates that the object is moving away from us. This was observed with many galaxies so the idea that space itself must be expanding was developed.

Cosmological Red Shift Cosmological Red shift: the wavelengths of radiated light are being constantly stretched (lengthened) as the light crosses an expanding universe. This was the main evidence for the Big Bang Theory Note: If an object is moving towards us then the light emitted from the object is shifted toward the blue end of the spectrum (towards the shorter wavelength area of the visible spectrum)

Explaining the Early Universe Big Bang Theory: Theory about the origin and evolution of the universe Suggests that because of the evidence we have for an expanding universe, the universe must have been more compact at an earlier time. They traced the paths backwards. Estimate that the present matter in the universe was compressed together into a hot, dense mass 13.7 billion years ago. This matter began to move outward after a massive explosion

Representation of the Big Bang Place colored, hole punched pieces in a balloon. Blow up the balloon and then pop it with a needle. The energy will expand the pieces. Student activity 6/G06LALB1.htm

Another theory to consider. Oscillating Theory: Suggest that the universe will expand to a certain point in time Then, due to forces of gravitation among the stars and galaxies, contract Scientists believe this will result in a “big crunch” followed by another Big Bang Like a bungee jumper: when they jump they accelerate due to gravity but eventually the force of the bungee will pull the jumper back.

Theories related to the formation of our solar system Solar System: The sun together with the eight planets and all other celestial bodies that orbit the sun Nebular Hypothesis: the sun and the planets formed when a large nebula condensed and collected together by gravity Nebulae: In between the stars in a galaxy, there are clouds of hydrogen gas and dust called Nebulae. If material in these clouds can be pulled together stars can form When a star forms its hot core remains surrounded by gas and dust and this leftover material can collapse and further collisions with other materials can occur eventually making a planet (see page 442)

Theories related to the formation of our solar system Stellar Collision Theory: a theory that suggests that our Sun and the planets were created from collisions between stars. The Nubular Hypothesis is believed to be more likely from observation of other star systems.

Unit to measure large distances Light year: The distance that light, which moves at km/s, travels in a year; equals 9.5 trillion Km. Light Year is a unit of measurement for extremely large distances. It is not a unit of time but a unit of distance The light from the moon takes 1.3 seconds to reach us so you are seeing the moon as it was 1.3 seconds ago. The light from Jupiter takes 41 minutes to reach us, so you see Jupiter as it was 41 minutes ago. When you look at objects far away in space, you are looking back in time

Activity 12-1A (page 439) Calculating the travel time to stars and the time required for light to travel from various points in the universe to Earth.

Major Parts of the Universe Interstellar matter: made up of gas (mostly hydrogen) and a small amount of dust Nebulae: clouds of dust and gas

Major Parts of the Universe Galaxy: forms when gravity causes a large, slowly spinning cloud of gases, dust and stars to contract. All the stars in the universe were formed in galaxies. There are three types of galaxies: Elliptical Galaxies: a galaxy that ranges in shape from a perfect sphere to an elongated but flattened ellipse and contains some of the oldest star in the universe.

Spiral galaxies: a shape for a galaxy with many long “arms” spiraling out from a center core made up of stars that formed long ago

Irregular Galaxy: a galaxy that has neither spiral arms nor an obvious central core, made up of a mix of newly forming stars and old stars.

Major Parts of the Universe Black Holes: a large sphere of incredibly tightly packed material with an extraordinary amount of gravitational pull created when a star collapses into itself. It is called a black hole because nothing, not even light, can escape the powerful gravitational field. Forms from a star 25 times the size of the sun Quasars: A region of extremely high electromagnetic energy that develops as the super massive black hole in the center of a galaxy attracts more matter into itself.

Major parts of the Universe Star: an object in space made up of hot gases, with a core that is like a thermonuclear reactor. There are giant and dwarf stars. Dwarf Star: low mass stars that start small and stay that way most of their life. Burn hydrogen fuel slowly and have long life Giant Star: Those stars that have the mass of the sun or greater. Burn hydrogen fuel faster and have a shorter life.

Birth of a Star Begins to form from the materials in a nebula Gravity acts on chunks of gas and dust, pulling them together Gravity keeps working and the mass grows, materials collapses on itself and contracts, now called a protostar (early star) Collects more mass, temperature of the core becomes very hot, atoms fuse together to form larger atoms Hydrogen atoms combine to from helium and this process called nuclear fusion creates a lot of energy and it is released and the star glows.

Stages in the Formation of a star

Life Cycle of Stars (3 paths possible)

Life cycle of a star There are three possible paths: 1) Low mass stars: Start small and exist as cool red dwarfs for most of their lives. They burn very slowly, can last for 100 billion years Can change into very hot, but small, dim white dwarfs and quietly burn out.

Life cycle of stars Path 2) Intermediate mass stars: Stars about the same size as the sun burn their hydrogen fuel faster, typical life is 10 billion years. After a long time they expand into a red giant Gradually sheds most of its material Collapses in on itself becoming a white dwarf, Then cools more and turns into a black dwarf, a dense dark body made up of mostly carbon and oxygen

Life cycle of stars Path 3) High mass stars: Stars with a mass 12 or more times the mass of the sun burn fuel really fast and become a red giant After using all the fuel it becomes a supergiant Then a massive explosion to get a supernova It can then collapse to give a black hole or a neutron star

Comparing Stars Activity: Using a similar worksheet shown on the next slide, research one of the stars. You will compare your star to the sun so you need all the same information about the sun. In the section “other information” find the magnitude of the star. Vega Canopus Sun Arcturus Betelgeuse Rigel Delta Orionis

The PDF version of this Worksheet is attached

Comparison of Celestial Bodies Website: and-Stars-animated-size-comparison

Science/Technology careers in Canada that are associated with Space exploration Astronauts Scientists – astronomers, physicists Engineers – electrical Doctors Pilots Technicians - lens makers

Scientific/Societal benefits and/or consequences of space exploration Consider each viewpoint Medical: Astronauts experience bone density loss. Help to study Osteoporosis Industrial: great deal of technology invented for space exploration is being used everyday. Ex. Cold weather clothing Agricultural: freeze dried food was invented for space travel but has spilled over in everyday life Meteorological: View hurricanes, storms from space to help study them Military: Observation of other countries

Brainstorm What are the risks associated with space exploration and travel? Equipment failure, death Leaving space junk, which can cause problems with future travel or satellites deu to collisions Astronauts are subjected to radiation from the Sun