Astronomy Notes (overheads)
Unit 4 ASTRONOMY
We know that:
Our universe is 13.7 billion years old.
The universe is expanding.
Our Sun will become a white dwarf after becoming a red giant in 5 billion years.
There is a black hole at the centre of the milky way galaxy
Our sun was recycled from other larger stars.
We know all this using information that we have gathered from light and radio telescopes. (And by making inferences using our b__________)
Chapter 7 Sky-Watching and the Solar system
7.3 THE EFFECTS OF PLANETARY MOTION
The Earth rotates on its axis every ____________.
It rotates towards the ________. We can infer this from the fact that the sun and moon and stars all rise in the _________ and move across the sky towards the ___________.
The Earth also revolves (orbits) around the Sun every ___________ days and is tilted on its axis.
When the northern hemisphere is tilted towards the Sun, Canada experiences _____________ and Australia experiences ___________.
We cannot see the stars that are ___________ of the Earth, from Canada. We can only see the stars that are on the opposite side of the __________ at night and the ones that are near Polaris, (also called the ___________ star).
We can collect information about the planets by sending probes to them. Why don’t we send piloted spacecraft instead? (317)
Answer Pg 285 1-3
THE SOLAR SYSTEM
Our solar System is composed of 8 planets and over 40 dwarf planets including Pluto, thousands of asteroids and comets that all orbit the Sun. The Sun is the only luminous object in our Solar System.
The only reason we can see the other objects is because they r__________ the Sun’s light.
The orbital period is the time it takes for one revolution.
It can be observed that as the distance from the sun increases, the orbital period of the planets ____________. (294)
Generally speaking, the 4 gas giants have ______________ surface temperatures than the 4 terrestrial (rocky) planets.
How do the densities of the 4 closest planets compare to the 4 gas giants?
The atmospheres of the 4 gas giants are composed mainly of …
7.5 Moons, Comets, Asteroids and Meteors
Any object that orbits another object is called a satellite.
The planets are satellites of the _________.
Moons
The Earth has one natural satellite called the ______________ and many artificial satellites.
Referring to table 1 Pg. 294. Jupiter has __________moons, Saturn has ___ and Uranus has _________.
In general the gas giants have __________ moons than the t___________ planets.
Some of the moons of Mars, Jupiter and Saturn have been investigated using s__________ p____________.
Asteroids
Between the orbits of Mars and ______________, there is a ring of thousands of asteroids called the asteroid belt. Astronomers believe that his ring of asteroids may have formed into a planet if the g___________ pull of Jupiter had not been so strong.
Moons and asteroids are rich in ____________ which we may someday mine.
Meteors
A meteoroid is a lump of rock or metal that is trapped by Earth’s gravity and pulled down through its atmosphere. When it passes through the atmosphere the friction causes it to become hot and vaporize and produce a bright streak, called a meteor or s___________ s____________.
If it makes it to Earth without completely vaporizing, it is called a meteorite.
Comets
Comets originate in the far reaches of our solar system and are therefore composed mainly of frozen matter. They have long elliptical orbits. When they come near the sun, the comet is warmed by solar radiation and the frozen matter becomes gases that we can see as a giant tail that points away from the sun.
Answer Pg 301 2-3 Pg. 312 7 19 20 21 29
The Nature of the Universe
Changing Ideas About the universe.
Even though we are traveling around the Sun at 30 km/s, and the Sun is in turn orbiting the center of the Milky Way, it doesn’t feel like we are moving. It is no surprise then that until the 1600s humans believed that the ___________ was at the center of the Universe. This is called the Geocentric, or _________ centered model of the Universe.
In the mid 1500’s Copernicus had presented mathematical evidence for a Sun centered Solar System? The invention of the telescope, and scientists like Galileo, helped to change people’s ideas.
We now know that our Sun is one of billions of stars that belong to the _________________ galaxy, and that the universe is composed of billions of galaxies.
8.1 Telescopes
The main purpose of the telescope s to gather l__________.
Refracting telescopes use lenses to gather light. The lenses cannot be more than 1.0m in diameter because if they are any larger the glass becomes too heavy and sags and distorts the image.
Reflecting telescopes (first constructed by N______) uses concave mirrors to gather light. These mirrors can be supported from underneath and can therefore be made much larger.
The atmosphere distorts the image, so telescopes are more effective if they are built on the top of m______________ where the a_____________ is thin.
Even better, put the telescope in orbit and avoid the atmosphere completely!
The Hubble telescope was put in orbit in 1990 and has created many amazing images.
Radio telescopes gather information from radio waves, which, like visible light, are part of the Electromagnetic spectrum.
Answer Pg 322 1(317) copy table 8.1
Pg. 327 5 6 7 Pg. 357 25 or 26
8.2 The Sun
The Sun makes up over 99% of the mass of our Solar system.
It is the source of all energy (Including l________) for the solar system.
Stars produce light through a process called nuclear fusion. In nuclear fusion, 2 hydrogen atoms combine to form a helium atom and in the process lose some mass which is converted into energy. (E=mc2)
Formation of Solar Systems
Copy figure 8.18 (pg. 334) into your notes.
Answer Pg. 338 5-8 and Pg 340 2 (339) 3 4 7 (339) 8(338) 9
If time: Bill Nye video , The Sun
8.3 Stars.
We can glean much information from stars by observing them. We know that the coolest stars are red (2000-3500 oC), medium hot stars are yellow (5000-6000oC) white stars are hotter (7500-11000oC) and the hottest are blue (25000-50000oC) (Refer to table 8.4 Pg. 344)
So the colour of a star tells us about its t_________________.
Stars also vary greatly in size from the smallest dwarf stars to the largest super giant stars. (Figures 8.26 and 8.28)
Scientists can also tell which elements are present in a star by observing them with spectroscopes. The spectroscope splits the light into patterns of colours. Each element has a characteristic corresponding pattern. Every star will have the pattern that corresponds to the elements h__________ and h_____________.
Some will contain heavier elements depending on their size and on whether they are created from recycle material. More massive stars can create heavier elements.
The amount of light energy that a star gives off is called its absolute magnitude. The apparent magnitude refers to how bright a star appears to be which depends on its absolute magnitude and on its d________ from us. For example, our yellow sun is not particularly hot or larger but it looks very bright to us (has a very high apparent magnitude) because ____________________________
All stars begin their lives in nebulas which are huge clouds of gases and dust, mainly H and He. All particles are in motion. The particle are attracted to each other due to g_________ and form larger and larger clumps of mass.
One direction of rotational motion dominates and the mass of particles starts to rotate. Gravity causes the mass to flatten into a disk shape. The center of the mass becomes hotter and more dense until the temperature reaches about 10 million degrees Celsius, which is the temperature at which nuclear fusion occurs.
The star turns on and generates light energy.
Small stars last for 10 to 100 billion years. The smaller the star the longer it takes to use up its hydrogen fuel.
When all the hydrogen has been converted to helium, the pressure holding the star together reduces, causing the star to turn into a red giant. Eventually the outer layers of gas drift away and the star turns into a white dwarf and then a yellow, red and black dwarf as it cools.
Large stars, (10 times larger than our Sun) form from larger n__________.
They only last for a few million years but are up to 5000 times as bright as our Sun.
When the hydrogen is used up the star becomes a red super giant. Then the core collapses inward and the outer layers explode outward as a supernova. The core materials become a neutron star and the gases drift away as a nebula to be recycled.
Extremely large stars (approximately 30 times the mass of the Sun) are very rare.
They use up their hydrogen in about 1 million years and become a red super giant. The core then collapses to produce a BLACK HOLE!!
Answer Pg. 347 5-8 and Pg 349 1 3 4 6 8
Chapter 8 Review Pg. 356 1-8 1 21 22
Chapter 9 The Mysterious Universe
The Origin of Planets
http://www.youtube.com/watch?v=B1AXbpYndGc&feature=fvst
Astronomers are continually investigating new evidence about the existence of planets; however it is challenging because planets are _______________ than stars and do not _______ ___________.
Clouds of p___________ orbiting stars such as Vega along with gravitational pull between stars and nearby planets that causes a _______________ wobble of the star’s motion provided evidence that the astronomers needed to determine that there are other planetary _____________ .
There are most likely three main stages in the formation of the solar system. Firstly, g__________ unites the rotating nebula that consists of ___________, ___________, ____________, ____________, and ice from nearby supernova explosions.
Secondly, this nebula’s rotation continued until a b_______ was formed in the centre later to be named the S___(approximately _______ billion years ago.) Cooler material gathered around the outside where some of the chunks eventually gathered more matter.
Thirdly, these smaller c__________ grew larger to form the Gas Giants -___________, ______________, _______________, and Neptune. These planets have similar chemical compositions to that of the Sun and as such it is theorized that they were created from the same matter.
Conversely, M__________, V____________, E________ and M___ are composed mainly of ___________, _________ that were left orbiting around the Sun. These large chunks of rocks and minerals collided in there orbits to eventually become p____________. (approx., 10 M yrs ago).
Asteroids, m_____________, and c__________ are the remaining minor rock and mineral bodies.