Space exploration

Unit 2 (textbook Unit 4) Space exploration

KWL Chart • Copy down the following chart (make it about a page long): • First, write what you already know about space (point form) – anything you can think of that you know for sure. • Then, write what you want to know about space that you don’t know already. • You will keep the table in your portfolio. At the end of the unit, you will take your chart out again and write down what you’ve learned.

What is all that stuff up there? • Any natural object in space such as a planet, a moon, an asteroid, a comet or a star is called a celestial body. • Early civilizations would make note of the movement of celestial bodies so that they would know when a good time to plant their crops would be. The stars and planets served as the first calendars.

Constellations • Groups of stars that make a pattern are called constellations. Ancient Greeks and Romans would label the constellations after characters from their mythologies.

Common Constellations • Three common constellations are: • Ursa Major (The Great Bear) • Ursa Minor (The Little Bear) • Orion Ursa Major Orion

Asterisms • Asterisms are smaller groups of stars that are present within constellations. Examples of these are: • The Big Dipper (In Ursa Major) • The Little Dipper (In Ursa Minor) • Orion’s belt (In Orion)

Movement of the Stars • Stars in the sky look as if they’re moving from East to West. This is caused by the Earth’s rotation on its axis. • If you look south, the stars look like they rise in the east and set in the west. • If you look to the north, the stars look like they’re all spinning (slowly) around one common point. This point is the North Star (Polaris). The stars “spin” around this point because the Earth’s axis points directly at Polaris – this makes it appear stable compared to the other stars.

Axes • Singular: axis Plural: axes • Axes are imaginary lines through a star, planet, moon or other celestial body that represent the point at which the planets revolve. All celestial bodies rotate on a central axis. • The Earth’s axis runs from the North Pole through to the South Pole. The Earth is actually tilted in space on it’s axis (the North pole isn’t the highest part of the Earth in space). One full rotation of the Earth takes about 24 hours. • Jupiter rotates the fastest, taking only about 10 hours. Venus takes the longest: about 243 Earth days.

Orbits and Ellipses • An orbit is the regular path of a celestial body around another, larger celestial body. • In our solar system, the largest celestial body is the Sun. The Sun follows the same path (orbit) every day. The line that the Sun’s orbit follows is called the ecliptic. It was named this because eclipses only happen when the Moon is close to crossing this line. • The Moon and Planets all follow paths (orbits) that are close to the ecliptic. • It was originally thought that the Sun, the Moon and all of the planets followed orbits that were perfect spheres. We have since learned that the paths they follow are actually ellipses. • Ellipses are oval-shaped. The reason for this is that while the Sun is large and near the centre of the solar system, the planets and other celestial bodies also influence the gravitational pull of each other. This results in the orbits being “stretched out” and gives the orbits their elliptical shape.

Orbits & Gravity • Orbits are the result of a perfect balance between the forward motion (momentum) of a celestial body in space, such as a planet or moon, and the pull of gravity on it from another celestial body in space, such as a large planet or star. • An object with a lot of mass goes forward and wants to keep going forward; however, the gravity of another body in space pulls it in. There is a continuous tug-of-war between the one object wanting to go forward and away and the other wanting to pull it in. • This simulation shows what might happen in the forward momentum of the Earth or Moon were to change.

Motion of the Planets • The planets all move at different rates around the ecliptic. The closer a planet is to the Sun, the faster it will move around its orbit. Therefore, Mercury will move the fastest. To remember the order of the planets from closest to farthest from the Sun, use this phrase: • My Very Earnest Mother Just Served Us Nine Pizzas (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto - Dwarf Planet) • Mercury and Venus are inside the Earth’s orbit around the Sun, and can only been seen setting just after sunset or rising just before sunrise. The planets outside the Earth’s orbit can be seen all night long, depending on their position relative to the Earth.

Movement of Asteroids and Comets • Comets and asteroids are two different things. Comets are made up of rocks and ice, and their tails can be seen only when they’re pushed into the inner solar system (near the Sun). Some comets have orbits that take them way out to the edge of our solar system. • Asteroidsare made of rock, and most orbit the Sun between Mars and Jupiter. Those that can been seen appear as if they move with the orbits of Mars and Jupiter.

Theories about the Universe • Just like with atoms, we know a lot about the universe because of different theories that people started developing a long time ago. • Some of these theories have been completely discarded, while other have been accepted or built on.

Aristotle • Aristotle thought that the universe was geocentric. This means that he thought the Earth was the centre of the universe, and that the sun, moon, stars and other planets revolved around it. • He based this theory on the fact that he did not see the patterns of the stars in the sky change, so he assumed that the Earth was not moving because if it was the star patterns would also move. • Aristotle was the first person to suggest that the Earth was a sphere based on shadows he saw on the moon during a lunar eclipse. He also proposed that the fact that the constellations that you can see change as you go from North to South showed that the Earth was a sphere.

Aristotle • Aristotle explained the apparent motion of celestial bodies by placing all of the celestial bodies seen from Earth on 22 concentric spheres. He said that these spheres moved at different speeds, which caused the different observations about the movement of the planets.

Ptolemy • Aristotle’s model of the universe did not explain all of the things that people observed. For example, if you watch Mars every night for a few weeks and map its position, you’ll notice that it travels in an ‘S’ pattern. It heads east, slows down, stops, and then heads west for weeks. • Ptolemy watched Mars very closely, and added to Aristotle’s model of the universe to explain the way that Mars moved.

Copernicus • Copernicus lived before the telescope was invented. He was the first to propose a heliocentric (sun centric) solar system. Using just his eyes, he observed that the movements of celestial bodies that others had noticed could be explained by the Earth rotating on its axis once a day and orbiting the Sun once a year. • Copernicus and others who supported him placed themselves in danger. Copernicus actually held off telling people about his theory until he was near death. Another astronomer, Bruno, who agreed publicly with Copernicus was burned at the stake.

Galileo • As we learned last year, Galileo invented one of the first telescopes. Using his telescope, he was able to make a lot of observations that no one could have before, and build on existing theories. • One important observation was that Venus had phases, like the Moon. This lent more evidence to the heliocentric solar system: Venus could not have phases if it did not orbit the Sun. • Galileo was put on trial and found guilty of heresy for publishing his theory. He was put in prison for the rest of his life.

Questions in Textbook Answer Questions 1 to 10 on page 375 in your book, EXCEPT NUMBER SEVEN!! Use pages 366 to 374 and your notes to help you.

Kepler • Kepler worked with a man named Brahe. They watched the planet Mars for weeks and tried to work out a model for how it moved. They found that a spherical orbit didn’t help to explain Mars’ movement. When they tried an elliptical orbit, everything fell into place. • Based on his work, Kepler developed 3 laws of planetary motion.

Kepler’s Laws of Planetary Motion • All planets move around the Sun in ellipses. • When a planet gets closer to the Sun it speeds up, when it’s further away it slows down. • The time a planet takes to revolve around the Sun is in direct proportion to how far away it is from the Sun (i.e. Mercury will orbit the fastest, Neptune/Pluto the slowest – depending on which one is considered the last “planet”).

Newton • Newton was the first to show that the force of gravity : • extends past the surface of the Earth • affects all celestial bodies, causing them to orbit larger celestial bodies (moons around planets, planets around the Sun, etc). • Newton invented the reflecting telescope (using mirrors & lenses instead of just lenses). • This allowed the telescope to be larger in size and give more exact images.

Astrolabes • Astrolabes are used to show how the sky looks at a specific place at a given time. This is done by drawing the sky on the face of the astrolabe and marking it so positions in the sky are easy to find. To use an astrolabe, you adjust the moveable components to a specific date and time. Once set, much of the sky, both visible and invisible, is represented on the face of the instrument. This allows a great many astronomical problems to be solved in a very visual way. Typical uses of the astrolabe include finding the time during the day or night, finding the time of a celestial event such as sunrise or sunset and as a handy reference of celestial positions. • astrolabes.org

Stone Circles • Stone circles are found all over the world, although most are in Europe. Archaeological evidence indicates that in addition to being used as places of burial, the purpose of stone circles was probably connected to agricultural events, such as the summer solstice. Although no one knows for sure why these structures were built, many of them are aligned with the sun and moon, and form complex prehistoric calendars. Although we often think of ancient peoples as being primitive and uncivilized, clearly some significant knowledge of astronomy, engineering, and geometry was needed to complete these early observatories. • http://paganwiccan.about.com/od/sacredplaces/p/Stone_Circles.htm

In your notebook: Describe for each planet (p. 400-401): • Size (Diameter!) • Shape (Don’t just say a sphere!) • What it’s made of • Approx. distance from the Sun (given in AUs – astronomical unit: 1 AU distance between the Earth and the Sun • Length of a day • Length of a year • Average temperature • Colour • Two interesting facts

Use pages 390 to 394 and 402-407 to answer the questions below: • A thermonuclear reaction is: • How many hydrogen atoms fuse together in the Sun to form helium? • How long has the Sun been giving off light? • How much longer will the Sun last? • What is solar radiation? • Solar radiation and what other force need to be in balance to keep a star from collapsing? • Describe: • Sun-spots: • solar flares: • solar prominences : • What is solar wind? • Why doesn’t solar wind affect us on Earth? • Moons are also called • How did the Earth’s moon form? • What is a dwarf planet? • How many Dwaft Planets are in our solar system? What are their names? • What is an asteroid? • What is the size range for an asteroid? • What is a comet? • Periodic comets have an orbit of less than 200 years. What is the periodicity of Halley’s Comet? When was it last visible from Earth? • What is a meteoroid? How is it different from a meteorite? • Answer questions 1-14 on page 411 in your book.

Canada in Space • Canadians have made several important contributions to space exploration: • The Canadarm: this piece of technology is mounted on the International Space Station and allows astronauts to sent out satellites, retrieve them, move large payloads, dock the space shuttles that arrive at the station, and help astronauts perform repairs and maintenance on the station. • The MOST: this stands for Microvariability and Oscillations of Stars Telescope. Developed by Canadians, this satellite is about the size of a suitcase and orbits the Earth in about 100 minutes. The satellite detects when the light from distant stars is dimmed slightly, which tells us that a planet has passed in front of it. These differences are extremely tiny so the equipment on the MOST must be very sensitive.

How Can We Explore the Universe? • Rocket Propulsion: Rockets transport astronauts and materials into space. At the beginning of the space program, animals were sent to make sure that the rockets were safe for humans. Some animals sent included several types of monkeys, chimpanzees, dogs and cats (mammals were preferred because they most resembled people). Rockets travel by thrust (think of letting go of a balloon that you’ve almost completely blown up). As the fuel on a rocket gets used up, parts of the rocket’s propulsion system break off from the rocket to make it lighter (and therefore require less fuel). 2. Space Suits: Space suits act as tiny spaceships that provide oxygen to breathe, temperature control, communication systems (imagine getting lost on a space walk with no one to call for help), and pressure control.

3. Satellites: these are artificial devices that orbit the Earth and send information. There are several types of satellites including communication satellites, remote sensing satellites, and telescope satellites like the MOST. • Satellites can travel in different types of orbits. The further away the satellite is from the Earth, the longer it will take to orbit: • Low Earth Orbit: between 300-500km above the Earth. These satellites travel around the Earth once every 90 minutes. • Geosynchronous orbit: satellites placed above the equator a distance of about 36 000km. These satellites take about 24 hours to make one orbit. Because they are rotating at the same rate as the Earth, these satellites appear to stay in the same place. Communication satellites are usually placed in geosynchronous orbit.

4. Probes: Probes are unmanned space crafts sent to other celestial bodies to gather information. They can fly past, orbit, or land on these bodies. All of the planets in our solar system have been visited by a probe, and a recent probe sent to Pluto is set to arrive in 2015. Probes send images and information directly back to the Earth. 5. Rovers: Rovers are like the ROVs that we learned about last year, only designed for outer space rather than the bottom of the ocean. Rovers have highly specialized programming so that they can problem solve and are designed to withstand extreme temperatures (freezing cold to blistering heat). They are designed to work all day long and conserve battery power at night.

6. Optical telescopes : these include both refracting (lenses only) and reflecting (lenses and mirrors) telescopes. Large observatories (labs that contain huge telescopes) are typically built high on mountaintops above most of the air so that they are not hindered by atmospheric conditions. 7. Radio telescopes : Radio telescopes collect wavelengths along the electromagnetic spectrum that are longer than visible light. Radio telescopes have large receivers that look like giant satellite dishes. They convert the radio signals to electric impulses that are used to discover details about celestial bodies that you would not be able to find out with optical telescopes.

Solar Systems, Galaxies and the Universe • Solar systems make up galaxies which make up the universe, just like cities and towns make up counties/provinces/states which make up countries which make up the world. • Solar systems consist of a star and all of the celestial bodies that orbit around that star. • Galaxiesare made up of several stars, planets, gas, and dust all held together by gravity. • The Universeconsists of all matter and energy.

The Big Bang Theory • The theory states that about 13.7 billion years ago, a tiny volume of space suddenly and rapidly expanded into a gigantic size. In a short time, all matter and energy in the universe was formed. The theory was first proposed by Georges Lemaître in 1927. The temperature of the Big Bang was over 1 000 000 000 oC. The universe has been cooling ever since.

The Oscillating Theory • Oscillating theory states that not only did the universe undergo a Big Bang, but that it will also someday undergo a Big Crunch. The idea is that the universe is closed and that there is enough matter to eventually stop the expansion of the universe, and through gravitational force, reverse it. • This is in contrast to open universe theories (like the Big Bang theory) which state that the universe is expanding and that the rate of expansion is increasing (getting faster) over time.

Theories about our Solar System • There are two main theories about how our solar system was formed: • Stellar Collision Theory: this theory proposes that the planets and our Sun came from collisions between stars (like the theory of how the moon was formed). • The Nebular Hypothesis: this theory states that the Sun and planets were formed when a large nebula condensed and formed together by gravity. It is suggested that a nearby star could have exploded and started the condensing of the nebula. This is the more accepted theory.

Distances in Space • We have already learned about astronomical units (AUs). 1 AU is equal to the distance between the Earth and the Sun (149 597 870.691 kilometres, or approximately 150 million). • Light years are used when distances get up to millions of AUs. Basically, if you are travelling at the speed of light, it will take you one year to cross the distance of one light year. Light travels at about 300 000km/s. One light year is just about 9.5 trillion (9 500 000 000 000) kilometres.

Major Components of the Universe • Nebula: a cloud of gas and dust in space, where stars are formed. • Elliptical Galaxies: a galaxy with a spherical to an elliptical shape that contains some of the oldest stars in the universe. Some look like a baseball, some like a football, some like a cigar. The largest galaxies in the universe are elliptical. • Spiral Galaxies: Galaxies made with long arms that spiral out from each other from a centre core. The Milky Way is a spiral galaxy.

Major Components of the Universe • High Mass Stars: Stars that have 12 or more times the mass of the Sun. These stars burn out very quickly. Become red supergiants and then collapse into neutron stars or black holes. • Intermediate Mass Stars: become red giants and supernova into nebula. • Low Mass Stars: become red giants and shrink into white dwarves.

Major Components of the Universe • Quasars: a region of extremely high energy that develops as the supermassive black hole in the centre of a galaxy attracts more matter into itself. • Black Holes: a large sphere of incredibly tightly packed material with a huge gravitational pull created when a star collapses on itself. Nothing, not even light, can escape the gravitational field. Because of this, not one knows what they look like.

Unit Review Starting on page 474, answer questions: • 2 to 14

Unit Review Starting on page 474, answer questions: • 18, 20, 21, • 23 to 25

Unit Review Starting on page 474, answer questions: • 29, 30, 32, 33, 37, • 39, 40, 43, 45 & 49

Space exploration