Grade 9 - Space Exploration

Section 1: Ancient Myths

Myths, folklore and legends were used to explain what ancient people observed in the night sky. 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. Aboriginal tribes – Algonquin, Iroquois and Narragansett believed the constellation Ursa Major was a bear running from hunters. 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. Ancient Egyptians - The Sun God – Ra – was carried in a sacred boat across the sky every day. Solstice represents the shortest and longest periods of daylight. The Ancient Celts set up megaliths, in concentric circles, at Stonehenge to mark the winter and summer solstices. Ancient African cultures set large rock pillars into patterns to predict the timing of the solstices as well. 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. Aboriginal Peoples of Southwestern Alberta used key rocks, which aligned with certain stars, in their medicine circles. Constellations are the groupings of stars we see as patterns in the night sky. There are 88 constellations and many are explained in Greek Mythology

Section 2: Telescopes

Telescopes allow us to see objects that are very distant in space. In 1608, Hans Lippershey made one of the first telescopes – but it was Galileo Galilei who made practical use of it. The observations he made included:
The moon had blemishes (mountains and craters like the Earth).
Sun spots indicated that it rotates on its axis.
Jupiter’s moons orbit the planet.
Planets were disk-shaped, but because the stars were still pinpoints, they were further away.

Galileo’s Approach to Inquiry: Galileo’s observations supported Copernicus’s Sun-centered model but not Ptolemy’s Earth-centered model. The reason for his beliefs was that, the moons he observed orbiting Jupiter, indicated that the earth was not the centre of the universe.

The first telescope designed was a simple refracting telescope. It uses two lenses to gather and focus starlight. Reflecting telescopes use mirrors instead of lenses to gather and focus the light from the stars. A process called 'spin-casting' today makes mirrors, by pouring molten glass into a spinning mould. The glass is forced to the edges, cooled and solidified.

Refracting telescope

Reflecting telescope

To improve the views of space, astronomers are able to access images from a telescope in space. Free from the interferences of weather, clouds humidity and even high winds, the Hubble Space Telescope, launched in 1990, orbits 600 kms above the Earth, collecting images of extremely distant objects. It is a cylindrical reflecting telescope, 13 m long and 4.3 m in diameter. It is modular (parts can be removed and replaced) and is serviced by shuttle astronauts.

Isaac Newton stated the law of universal gravitation eighty years after Kepler’s contribution about elliptical orbits of the planets. Newton’s law states that there is a gravitational force between all objects that pulls them together. An orbit is the result of the attractive force of gravity balancing the straightforward movement of a planet because of velocity.

Section 3: The Spectroscope

Spectroscopy is the Science of Colour. Isaac Newton passed a beam of light through a prism to produce a spectrum of colors. If you pass the light through a narrow slit before sending it through a prism (a spectroscope is a device that does this) the spectrum will be in more detail. Joseph von Fraunhofer used a spectroscope to observe the spectrum produced by the Sun. He noticed dark lines, called spectral lines, but didn’t know what they meant. He found these spectral lines throughout the solar system.
The significance of the spectral lines was discovered about 50 years later when Kirschoff and Bunsen, two chemists used a spectroscope to observe various chemicals when they were heated. They found some of the lines missing in some of the chemicals. Each particular element had its own unique spectral lines. This led to the science of spectroscopy – the study of spectra, as a part of chemistry. They found that there were three types of spectra.

Astronomers refract the light from distant stars to determine what the star is made of. Stars have dark bands in distinct sequences and thicknesses on their spectra. Each element that is present in the star creates its own black-line ‘fingerprint’. By attaching spectroscopes to their telescopes, astronomers are able to observe a star’s spectra, but because the distant stars are much dimmer than our Sun, only some of the elements in the spectra can be identified. Those that cannot be identified remain as inferences, based on what astronomers know about certain types of stars.

The Doppler Effect

A change in the pitch (frequency) of sound waves because they are stretched or squeezed is known as the Doppler effect. Changes in the sound waves can be measured to determine how fast and in what direction a light-emitting object is moving. The spectrum of an approaching star shows the dark bands shifting to the blue end of the spectrum, whereas, the shift is to the red part of the spectrum if a star is moving away from the Earth.

Law enforcement officers detect the speed of an approaching vehicle by using a radar gun, which sends out a radio signal and receives one back from the vehicle. To determine the speed of the vehicle, the hand-held device records the difference in the outgoing wavelength and incoming wavelength.

Section 4: Modern Telescopes

Bigger telescopes enable astronomers to discover new bodies in space. Sir William Herschel built a huge reflecting telescope and discovered the planet Uranus with it in 1773. The largest refracting telescope was built at the Yerkes Observatory near the end of the nineteenth century. With it, Gerald Kuiper discovered methane gas on Saturn’s moon, Titan, and two new moons of Uranus.

The technique of using a number of telescopes in combination is called interferometry. When working together, these telescopes can detect objects in space with better clarity and at greater distances than any current Earth-based observatory.

Distance to the Stars

Telescopes enable astronomers to see further into space and identify distant stars. The problem they still have is how far are they from the Earth? The answer to this question lies in two methods. Triangulation and Parallax are two ways to measure distances indirectly, on the ground, or in space.

Triangulation is based on the geometry of a triangle. By measuring the angles between the baseline and a target object, you can determine the distance to that object. To measure the distance indirectly, you need to know the length of one side of the triangle (baseline) and the size of the angles created when imaginary lines are drawn from the ends of the baseline to the object.

Parallax is the apparent shift in position of a nearby object when the object is viewed from two different places. Astronomers use a star’s parallax to determine what angles to use when they triangulate the star’s distance from the Earth. The larger the baseline, the more accurate the result. The longest baseline that astronomers can use is the diameter of Earth’s orbit. Measurements have to be taken six months apart to achieve the diameter of the orbit.

Section 5: Radio Telescopes

With the development of radio telescopes, astronomers gain an advantage over optical telescopes, because they are not affected by weather, clouds, atmosphere or pollution and can be detected day or night. Much information has been gained about the composition and distribution of matter in space, namely neutral hydrogen, which makes up a large proportion of matter in our Milky Way galaxy.

Radio telescopes are made of metal mesh and resemble a satellite dish, but are much larger, curved inward and have a receiver in the center. In 1932 Karl Jansky built a radio antenna that was able to identify radio waves from space. Grote Reber built a radio dish based on Jansky’s antenna findings, where he 'listened' to the sky during the 1930’s. He discovered that the strongest radio waves came from specific places in space. The static Rober heard became louder when he tuned into these radio objects. The loudest being our Sun in the Milky Way Galaxy.

Radio telescope waves provide data, which astronomers graph, using computers to store the data and false color it to produce images of the radio waves, which are coded to the strength of the waves. Blues for low intensity, and as the signal gets stronger the colors go through greens, yellows, reds and whites. Radio observations have provided a whole new outlook on objects we already knew, such as galaxies, while revealing pulsars and quasars that had been completely unexpected.

Telescopes can now be connected without wires, thanks to computers and clocks. This method is called Very Long Base Interferometry ( VLBI ). With this technique, images 100 times that of the largest optical telescope can be captured. This is done by capturing images from any or all radio telescopes in the world.

Section 6: Rockets

The science of rocketry relies on the basic principle that For every action – There is an equal and opposite reaction. There are three basic parts to a Rocket:

The structural and mechanical elements are everything from the rocket itself to engines, storage tanks, and the fins on the outside that help guide the rocket during its flight.

The fuel can be any number of materials, including liquid oxygen, gasoline, and liquid hydrogen. The mixture is ignited in a combustion chamber, causing the gases to escape as exhaust out of the nozzle.

The payload refers to the materials needed for the flight, including crew cabins, food, water, air, and people.

Rockets need combustible fuel to make them fly. All fuels create exhaust which comes out the end of the rocket. The speed of the exhaust leaving the rocket is called the exhaust velocity, which determines the range of the rocket. The gravitational escape velocity had to be achieved (28,000 km/h), if humans were to venture into space. Robert Goddard launched the first liquid fuel rocket in 1926. The rocket was staged (having more than one section that drops off once its fuel is used up, making the rest of the rocket lighter and able to fly higher.)

In the 1960’s the Americans and the Russians were racing to launch spacecraft into orbit using rockets. They needed to use computers to calculate and control their orbits. The first computers on the ground (which filled large rooms) controlled the spacecraft in orbit. As computers became smaller they were put onboard the spacecraft and worked with computers on the ground to control the flight. Their vital role was to calculate orbits, locate satellites (and space junk), collect, store, and analyze data and to maneuver around these obstacles in orbit.

A technique called gravitational assist is a method of acceleration which enables a spacecraft to achieve extra speed by using the gravity of a planet. The planet’s gravity attracts the craft causing it to speed up and change direction (a slingshot effect), sending it on to the next planet.

Satellites can be natural – small bodies in space that orbit a larger body (the Moon is a satellite of the Earth ), and they can be artificial – small spherical containers loaded with electronic equipment, digital imaging and other instruments that are launched into Earth’s orbit to perform one of four functions:

1. Communication Satellites

These satellites provide 'wireless' technologies for a wide range of applications. Digital signals have resulted in clearer communications and more users

2. Satellites for Observation and Research

A geosynchronous orbit is one that enables a satellite to remain in a fixed position over one part of the Earth, moving at the same speed as the Earth. Numerous applications are now possible including:
Monitoring and forecasting weather
LANDSAT and RADARSAT (are not in geosynchronous orbit) – follow ships at sea, monitor soil quality, track forest fires, report on environmental change, and search for natural resources.
Military and government surveillance

3. Remote Sensing

Those satellites in low orbits perform remote sensing – a process in which digital imaging devices in satellites make observations of Earth’s surface and send this information back to Earth. The activities include providing information on the condition of the environment, natural resources, effects of urbanization and growth.

4. Personal Tracking Devices

The Global Positioning System (GPS) allows you to know exactly where you are on the Earth at any one time.

Section 7: The Solar System

A solar system is made up of a star and the objects that orbit around it. In our solar system, there are eight planets orbiting the Sun. A planet is a large object that orbits a star. Form neares to the sun, the planets in our solar system include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The planets travel around the sun in elliptical or nearly circular orbits.

The inner planets are closer to the Sun than the asteroid belt and have surfaces made of rock. These planets are Mercury, Venus, Earth, and Mars. The outer planets are beyond the asteroid belt and have surfaces made of gases. These planets are Jupiter, Saturn, Uranus, and Neptune. Pluto was once known as the ninth planet. Pluto’s elongated orbit and small size were different from the other planets. Because of this, scientists debated whether Pluto should be classified as a planet. In Aug 2006, the International Astronomical Union officially reclassified Pluto as a dwarf planet. Other dwarf planets include Ceres and 2003 UB313, which is larger than Pluto but farther from the Sun.

Planet's unique features:
Jupiter: has the great red spot (aka red eye), which is a huge storm that has been blowing for over 400 years. It is believed that combination of sulfur and phosphorus are in Jupiter's atmosphere gives this storm its red color.
Saturn rings: First observed by Galileo in 1610. They are made of ice and rocks ranging in size from pea size to rocks larger than a house. Jupiter, Uranus and Neptune also have faint rings that are more difficult to observe.
Venus: The surface of Venus shows evidence of violent volcanic activity in the past. Venus has shield and composite volcanoes similar to those found on Earth. Long rivers of lava have also been observed on Venus.
Mars rocks! The dark boulders on the surface of Mars are volcanic rock fragments that have been found on Mars. These rocks look similar to rocks found near lava flows on Earth.

A moon is a natural object (natural satellite) that orbits a planet. Different planets have different numbers and sizes of moons. Generally, the outer planets have more moons. The Earth has only one moon while Jupiter has at least 63 moons. Saturn has 47 moons, Uranus has 27 and Neptune has 13.

An artificial satellite is an object that is put in space by man to orbit around the earth or other planets. These may be to monitor weather or conduct various forms of communication.

Moons vary in size. Ganymede is the largest moon in the solar system. In fact Ganymede is larger than Pluto and Mercury. The Earth's moon is also larger than Pluto and is clearly visible without a telescope.

When small objects in space collide with larger objects, a crater is formed. Craters are bowl-shaped holes on the larger object.

A comet is a mixture of frozen gases, ice, dust, and rock that moves in an elliptical orbit around the Sun.

An asteroid is a rock that revolves around the Sun. Most of the thousands of asteroids in the solar system are located between Mars and Jupiter in the asteroid belt.

An object that crosses paths with Earth and enters the atmosphere is called a meteor. Most meteors burn up before they reach the ground. When a meteor lands on the ground, it is called a meteorite.

Chelyabinsk meteor - 2013

Lesson 4: Stars

A star is an object that produces its own heat and light energy. Stars go through stages from beginning to ending depending on how much hydrogen tha star contains. The star's cycle ends when it stops giving off energy.

All stars form out of a nebula. A nebula is a cloud of gases and dust. Gravity pulls the mass of nebula, which contains a lot of hydrogen atoms and as the atoms move closer they collide with each other producing heat. The temperature increases and when the temperature reaches 10 million degrees Celcius, the hydrogen atoms combine to form Ehlium. This process produces huge amounts of heat and light. This marks the beginning of the formation of a star.

The sun is a star, like other stars, it uses hydrogen as the source of energy. As the heat in the sun increases, it forces the hydrogen at the endge of the sun to expand into space, as the hydrogen moves further away from the center of the sun, it cools slightly and turns red. This stage of the star is called a red giant.

The Sun is 1.4 million km in diameter. Its temperature is about 15 million degrees Celsius. 600t of hydrogen are converted, by nuclear fusion, into helium per second. This is the energy released from the Sun. The Sun emits charged particles in all directions. This solar wind bombards the Earth at 400km/s, but the magnetic field of the Earth protects us.

Eventually, all the helium is gone and the star begins to cool off and shrink becoming a white dwarf. A white dwarf is a small dense star that sines with a cooler white light. This is the end of the cycle for medium sized stars.

Stars that start with larger amounts of hydrogen (larger stars) end their cycle differently. After they become red giants the atoms at the core become so hot that they combine to form iron atoms. Eventually the iron gets so hot and explodes into a supernova. Supernovas shine brightly for days or weeks then they fade away.

If a star is very massive, it may end its life as a black hole. A black hole is an object that is so dense and has such powerful gravity that nothing can escape from it,not even light.

The sun is a medium sized star with a temperature of around 6000 degrees celcius. Giant stars are about 100 times larger than the sun and super giant stars are 1000 times larger. Neutron stars are the smalles stars.

Stars that form patterns are called constellations. Constellations were often named after animals, characters from stories, or familiar objects. Some constellations have been extensively useful to both ancient and modern travelers. For example, if you can see either the Big Dipper or the Little Dipper in the night sky, you can follow the line that their stars make to find Polaris, the North Star. If you travel in the direction of Polaris, you will be moving north. If you ever become lost in the woods or at sea, look for Polaris (North star) in the night sky. It will help guide you to safety.

The ancient Greeks divided the sky into 12 sections. They named some constellations after characters from Greek myths, such as Orion, a hunter, and Hercules, a hero.

Light Years

After the sun, the next closest star is called Proxima Centauri and is about 40,000,000,000,000 km away. This distance is so huge and becomes difficult to remember and comprehend. We can use the unit light year, which is equal to the distance that light travels in a year, and is equal to 9.5 billion kilometers. Proxima Centauri is 4.2 light years away from the earth.

Clusters and Binary Stars

Some stars form clusters that may contain more than 100,000 stars. Clobular clusters are shaoed like a sphere. When two stars are close to each other, or somehow overlap and are seen as though they were only one star, they are called binary stars. the prefix -bi stands for 'two'. A star that seems to be blinking might actually be a binary star where one of the stars, the dimmer one, blocks the light from the brighter star.

Galaxies

A galaxy is a huge very distant collection of stars. Each galaxy holds billions of stars.

Galaxies differ in size, age, and structure. Astronomers place them in three main groups based on their shapes: spiral, elliptical, and irregular.
A spiral galaxy looks like a whirlpool. The spiral arms can be tightly or loosely wound around the galaxy’s core, and they often contain a great deal of dust. Some spiral galaxies are barred galaxies. A barred galaxy has a “bar” of stars, gas, and dust through its center. The spiral arms emerge from this bar.
An elliptical galaxy is shaped a bit like a football. It has no spiral arms and little or no dust.
An irregular galaxy has no recognizable shape. The amount of dust and gas varies. The irregular shape may have been caused by collisions with other galaxies.

Our solar system is part of the galaxy called the Milky Way. The stars you see in the sky are part of the Milky Way galaxy. The Milky Way is a spiral galaxy. The stars are grouped in a bulge around a core. All of the stars in the Milky Way, including our Sun, orbit this core. The closer a star is to the core, the faster its orbit is. Several spiral arms extend out from the core. Our solar system is located on one of these spiral arms. The arms contain most of the Milky Way’s gas and dust. We cannot see the center of the Milky Way, because there is dust between us and the core. However, from Earth we can see more stars when we look in the direction of the galaxy’s center than when we look in other directions.

The Big Bang Theory

The Big Bang Theory hypothesizes that the universe started with a big bang a single point and has been expanding ever since. Scientific evidence indicates that the big bang happened 13.7 billion years ago.

Astronomers think the galaxies must have been closer to each other in the past. The early universe was very dense, and its temperature was high. At the beginning moment, the universe was extremely tiny, hot, and dense. From this tiny beginning, the universe expanded rapidly. This expansion sent matter out in all directions.

The galaxies continue to move outward. Evidence for the big bang comes from background radiation. Background radiation comes from all directions in space. This radiation is left over from the beginning moments of the universe.

How did Earth form?

Scientists think that Earth is about 4.6 billion years old and theorise that the Earth and its atmosphere developed in a series of stages. The process began in the nebula that formed the Sun. Dust and ice particles moved within the nebula, occasionally colliding. They merged and stuck together. The clumps of particles grew until they became the young Earth, or proto-Earth. Over time, proto-Earth became large enough that its gravity could hold an atmosphere. Scientists believe that the atmosphere did not initially contain oxygen, as it does today. Atmospheric oxygen developed as a waste product of photosynthesis.