Download Space 8.1 notes

UNIT 4: THE STUDY OF THE UNIVERSE: CHAPTER 8: OUR PLACE IN SPACE
8.1 – Touring the Night Sky
Astronomy is the study of objects that exist beyond the earth or in space.
Universe - everything that physically exists, including energy, matter and even empty space. It is
made up of celestial objects, objects in space like galaxies, sun, stars and moons
The solar system consists of the sun and all the objects that travel around it.
GALAXIES
 Galaxies are a huge collection of gas, dust, billions of stars, planets and other
objects. There are billions of galaxies in the universe.
 We are in the Milky Way Galaxy.
STARS IN GENERAL
 A star is a large celestial body made up of hot gases. It releases large
amounts of energy and is held together by its own gravity, keeping it intact
 Stars are considered luminous because they produce and give off their
own light.
SUN
 The sun is an average sized star, as most stars are significantly larger than
our sun
 The sun looks large to our eyes because it is fairly close to Earth
 The sun gives off visible light and energy, but only a small amount of the
Sun’s light reaches the earth. It is enough to provide life on Earth
PLANETS
 A planet is a large celestial object that orbits around a star
 There are 9 planets that orbit around the sun. Mercury is closest to the sun and Pluto is the
farthest
 The first four planets are called the terrestrial planets – they are made of rock
 The farther four planets are called the gas giants - they are made of gases and liquids
 Planets are non-luminous, because they cannot produce and emit their own light. We can see
planets, because they reflect light
 Earth is the fourth largest planet in the solar system. Earth is a planet composed of rock and
supports life.
MOONS
 Satellites are celestial bodies that travel around a planet or dwarf planet
in a closed path called an orbit. The moon is an example of a satellite.
 Not all planets have moons, but Earth has a satellite called the Moon. It
appears to be the largest object in the night sky because of its distance to
the earth. The actual distance is 384000 km.
SCIENTIFIC NOTATION


Astronomers work with both very large and very small numbers. We tend to use a simpler form of
these numbers, using scientific notation
It is a number between 1 and 9 multiplied by powers of 10
𝒂 × 𝟏𝟎𝒏
Rules for Scientific Notation

When a large number is converted to scientific notation, the decimal place moves to the left
Ex. 1 300 000 =
(your exponent will be
)
(The sun is this many times the volume of Earth)

When a small number is converted to scientific notation, the decimal place moves to the right
Ex. 0.0505 =
(your exponent will be
)

When expanding scientific notation to a large number, the decimal place moves to the right
Ex. 1.5 x 108 =
(The distance between the sun and the Earth)

When expanding scientific notation to a small number, the decimal place moves to the left
Ex. 9.8 x 10-3 =
HMWK:
Pg 308 # 2 - 9