Space exploration

early views about the cosmos https://www.youtube.com/watch?v=KaOC9danxNo

Special cosmological events Humans have always looked up to the night sky in wonder- looking at planets and stars and the moon- and wondering how it all worked together Early civilizations such as the Mayans and Egyptians built monuments to honour the seasonal position of stars

Other Cultural Events with Space Myths, folklore and legends were used to explain what ancient people observed in the night sky. • Ancient African cultures set large rock pillars into patterns to predict the timing of the solstices as well. • First Nations people of the Pacific Northwest - believed the night sky was a pattern on a great blanket overhead, which was held up by a spinning 'world pole' resting on the chest of a woman named Stone Ribs. • The Mayans of Central America built an enormous cylinder shaped tower, at Chichen. Itza, to celebrate the two equinoxes. • The Ancient Egyptians built many pyramids and other monuments to align with the seasonal position of certain stars. • Inuit in the high Arctic - used a mitt to determine when seal pups would be born, by holding the mitt at arm's length at the horizon. • Aboriginal Peoples of Southwestern Alberta used key rocks, which aligned with certain stars, in their medicine circles.Ancient cultures tried to explain the motions of the stars and planets. • The Ancient Celts set up megaliths, in concentric circles, at Stonehenge to mark the winter and summer solstices.

2 special annual events are called solstices 1) Summer Solstice- the longest day of the year June 21 2) Winter Solstice- the shortest day of the year December 21 Why might people have been interested in tracking these things?

Another special phenomenon is called the equinox which occurs in spring and fall The equinox is when the length of the day and night are the same

Models of planetary Motion 1) Geocentric Model Aristotle, 2000 years ago, created the Earth-centered model where he believed everything revolved around the Earth. How many things actually revolve around the earth? There were many things the model could not explain

Geocentric Model Issue How could it be true that Mars, Jupiter and Saturn orbited around the Earth when sometimes they looped in the sky?

2) Heliocentric Model In 1530 Nicholas Copernicus proposed the heliocentric model which stated that the Earth and other planets revolved around the Sun This model explained many of the issues that there were with the geocentric model

Let’s Compare them Both

Think about it Why would previous views of space matter to what we know of today?

Definitions Orbit- a celestial body’s path Ellipse- oval shape What does the Earth orbit around? What does the moon orbit around? What does the sun orbit around? Ellipse- oval shape

Think about it When planets move in ellipses their speed does not remain constant- the closer they are to the “narrow part” of the ellipses the faster they move Their temperature varies also as they move closer and further from the sun Do you expect the earths orbit to be more elliptical or circular? Why?

The Distribution of Matter in Space

I Can… Describe the different forms of matter in space (e.g., stars, star systems, galaxies, Nebulae)

What is a Star? Stars are glowing balls of gas that are made mostly of hydrogen They can vary in the colour that they give off, their size and their density Hotter stars look blue and cooler stars look red

Ejnar Hertzsprung and Henry Norris Russell compared stars surface temperature to their brightness (luminosity) They discovered that there is a link between temperatures and brightness of stars This is called the Hertzsprung-Russell Diagram

Let’s Draw!! Copy out the pictures on page 385 into your notes Be sure to include the axis and stars names Supergiants Giants Sun White Dwarf Main Sequence

The Birth of a Star Stars form in a region of spaced called a nebula (made of hydrogen, helium, oxygen, nitrogen and carbon) This matter is called interstellar matter and came from exploded stars

Example: Crab Nebula Notice how much matter there is in the nebula

Steps of a Star’s Birth 1) Some of the material in the nebula can collapse into a rotating cloud of dust and gas 2) The temperature climbs 3) If it gets hot enough it will glow 4) The is called a protostar- first stage in a star’s formation

The Life and Death of a Star The new star may become Sun-like or massive These stars convert hydrogen to helium in their core (nuclear reactors) These stars can remain stable for millions of years (or so they think)

When the hydrogen runs out the star’s gravity pulls in the other matter and can turn into a red giant (if it is a sun-like star) or a supergiant (if it is a massive star) Eventually the reaction in the red giant star quits, the star shrinks becoming a white dwarf and then a cool dark black dwarf

The massive star explodes when it runs out of fuel and goes through a supernova From there is can turn into a neutron star or a black hole A black hole is a very dense remnant of a star with gravity so strong that light can’t escape from it

Black Holes Black holes are invisible to telescopes Black holes were discovered because of how materials react near them

Draw Again! Copy the diagram on page 386 into your notes to help you keep track of the life of a star

Star Groups AKA Constellations Constellations are groupings of stars that we see in the sky Early civilizations drew pictures in the stars and named them constellations

Galaxies A galaxy is a grouping of millions of stars, gas and dust which is held together by gravity Our galaxy is called the Milky Way– it is a spiral galaxy which looks like a CD with a marble in the middle Other galaxy shapes are elliptical and irregular

Elliptical Galaxy

Irregular Galaxy- No Specific Shape

Our Solar Neighbourhood

I Can… Identify evidence for, and describe characteristics of the planets and compare these to Earth

The Sun The Sun is the center of our solar system The Sun is almost a million times bigger than earth Its surface temperature is 5500 degrees and the core is 15 000 000 degrees The sun gives off charged particles- it is called solar wind and travels 400km/s We are protected by our magnetic field

The Planets The planets are very different from one another They are divided into two groups Terrestrial: earth-like and rocky nearer to the sun Jovian (gaseous)- large and made of gases, further from the Sun

Terrestrial Planets Mercury, Venus, Earth, and Mars

Jovian Planets Jupiter, Saturn, Uranus, and Neptune

Just For Fun http://www.youtube.com/watch?v=h3ppbbYXMxE

Other Bodies in the Solar System Asteroids- small rocky or metallic bodies that travel in space Can be a few meters to several hundred km across Can we stop an asteroid? https://www.youtube.com/watch?v=Agdvt9M3NJA

Comets- described as “dirty snowballs” made up of dust and ice that travel through space. They tails can be seen when they get closer to the Sun

Meteoroids – a rock in space, no particular gravitational path Meteors – rock from space pulled into earth’s gravitational pull Meteorites – space rock falling towards earth’s surface Are small pieces of rocks flying through space from as small as a grain of sand to as large as a car When it gives off light it is called a meteor or a shooting star

Describing the Position of Objects in Space

I can… Describe and apply techniques for determining the position and motion of objects in space (relative position - altitude and azimuth), (elliptical orbits - string on 2 pivot points), (distances - triangulation).

Tracking Objects in the Solar System Eclipses occur when one celestial body moves in front of another one Because we understand orbits we can predict eclipses

Locating Objects in Space There are 2 different measurements that we need in order to pinpoint an object in the sky and communicate where it is to other people Think of the sky like a bowl, how could you tell someone where a dot was on the inside of the bowl?

Azimuth The first measurement we use is called the azimuth, it tells us what direction to face. The direction for azimuths are similar to the directions on a compass Note: on a compass there is a north/south line dividing the compass What is the north/south line in Lethbridge? System one- North, East, South, West System two- degree 0-North, 90-East, 180-South, 270-West

ALTITUDE The other measurement is called altitude and it tells you how high up to look from the horizon If it was exactly on the horizon it would be 0 degrees If you were looking straight up then it would be 90 degrees What numbers can be used for altitude?

Zenith The highest point in the sky is called the zenith.

Let’s check it out! http://astro.unl.edu/classaction/animations/coordsmotion/altazimuth.html

Clinometer Use Practice: Make and use a clinometer to measure the angle of height for objects in the room

Think about it! Observation Point Why would it matter where the observer is when they are given azimuth- altitude measurements to find a specific planet?

Video http://www.youtube.com/watch?v=2Aw830kmLdU

Determining the Motion of Objects in Space Stars appear to stay in one place in the sky because they are so far away from us Planets move in relation to the stars fairly quickly (we can see changes in days or weeks) The path in with the Sun moves in the sky is called the ecliptic Check out the diagram on page 404 to see the “celestial sphere”