Earth, Space, Time: Grade 9 Science IB Flashcards
What was the Big Bang?
- The Big Bang is the most widely accepted explanation regarding the origins and composition of the universe.
- When matter began expansion
What is an Astronomical Unit?
- Symbol is AU
- Used to measure distances within the solar system
- One astronomical unit is equivalent to 150 million kilometres
- One astronomical unit is equivalent to the average distance between the Earth and the Sun
What is a Light Year?
- Symbol is LY
- Used to measure distances outside our solar system
- One light year is equivalent to 9460 billion kilometres
- One astronomical unit is equivalent to the distance travelled by light in one year
The Sun and the Solar System:
Key words
- Star
- Kuiper Belt
- Oort Cloud
- Earth Position
- The Earth rotates around a star called the Sun
- Earth is the 3rd planet from the Sun
- Beyond Neptunes orbit is the Kuiper belt, it is 30 to 50 AU away from the Sun and is made of billions of icy objects like comets
- Beyond the Kuiper belt is the Oort Cloud, it is shaped like a ball, it surrounds the entire solar system. The Oort Cloud is between 10 000 and 100 000 AU from the sun and is made up of over 1000 billion comets
The Milky Way:
- Number of stars
- Composition of a galaxy
- Galaxy sizes
- Diameter of Milky Way
- Position of sun
- Andromeda Position
- 200 billion stars
- Galaxy = group of stars, gas, and dust
- There are different sizes of galaxies some are a few million stars others contain over 1000 million stars.
- The diameter of the Milky Way is about 130 000 light years
- The Sun is located at the end if one of its arms about 32 000 light years away from the center.
- Andromeda, a neighbouring galaxy to ours is 2.5 million light years away
A cluster of galaxies: the Local Group
- Composition
- How
- Area x^2
- # of galaxies
- The Milky Way is part of a cluster of galaxies called the Local Group.
- A galaxy cluster is held close together by gravitational forces in the same sector of the Universe.
- The Local Group contains about 50 galaxies and covers an area of about 10 million light years.
A supercluster of galaxies: The Local Supercluster
- What?
- How?
- # of galaxies
- # of superclusters
- Name
- Distance covered
- The Local group is part of a supercluster called the Local Supercluster.
- A supercluster is a group of galaxies that are held close together by gravitational forces.
- One supercluster can contain a billion galaxies.
- There are millions of superclusters in the
Universe. - The Local Supercluster covers a distance of 100 million light years.
List the Conditions Conducive to the Development of Life:
- The Habitable Zone
- A Circular Orbit
- An Atmosphere
- The Ideal Mass
- Water
- A Lithosphere
What is the habitable zone?
- Planet must orbit at a particular distance, called the habitable zone
- Varies depending on the strength and size of a star
- Allows warmer to stay in liquid form
What is a circular orbit?
What does a planets orbit determine?
Key word - energy
- The shape of a planets orbit determines how the quantity of energy they receive will change, thus influencing the temperature
What is an atmosphere
- A planets atmosphere must be able to protect life forms from dangerous solar radiation
- A planet must also have atmosphere that allows the water cycle to take place
What is the Ideal Mass
- Mass determines the strength of a planet’s gravity
- Big planets have a stronger gravitational field therefore attracting the particles to form an atmosphere, however to strong of a gravitational force the planet will retain Helium a gas that is not necessary for life to develop.
- On the other hand, a planet with a small mass will not have enough gravity to hold the gas particles necessary for the development of an atmosphere
Why is water essential?
- A planet needs liquid water because water is essential to the development of the first molecules that lead to the start of life forms
What is essential about a Lithosphere?
- A planet needs a solid surface for simple molecules to be able to develop into more complex ones.
What is pasteurization?
Pasteurization is the partial sterilization of liquids such as milk, orange
juice, wine, and beer, as well as cheese, to destroy disease-causing bacteria
and other undesirable organisms. The process is named for the French
scientist Louis Pasteur, who discovered in the 1860s that undesired bacteria
could be prevented in wine and beer by heating it to 57°C for a few minutes.
Milk is pasteurized by heating it for 30 min followed by rapid cooling. The
harmless lactic acid bacteria survive the process, but if the milk is not kept
cold, they multiply rapidly and cause it to turn sour.
In short, pasteurization is the process of heating and cooling in order to kill bacteria.
