Topic 11 Flashcards
Name the 8 planetary bodies in order
- Merury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
WHat are the inner 4 terrestrial planets and what are they made of?
-Mercury, Venus, Earth, Mars. Rocky with a core of iron
Do terrestrial planets have rings?
No
Which terrestrial planet does not have an atmosphere with large molecules
Mercury
WHich are the only 2 terrestrial planets with Moons
Earth and Mars
WHat are the outer 4 gas giant planets? What are they made of
Jupiter, saturn, Uranus, Neptune, they are gaseous with liquid interiors
What are 4 characteristics of gas giants
-have many moons
-relatively large diameter and mass
-atmosphere made predominantly of hydrogen and helium with some methane and ammonia
-all have rings
What are some key features of dwarf planets
-THey orbit around the Sun
-THey don’t satellite another planetary body
-Have a near spherical or consistent shape
-different to a normal planet due to size and eccentric orbit
What are the 4 closest dwarf planets
Pluto, Eres, Ceres, MakeMake
What is an asteroid?
iron and silicate based rocks, found inbetween Mars, and Jupiter in the Asteroid belt, with a diameter of less than 10km
What is a comet
dust, rock, and ice balls that come from the outer solar system and orbit the Sun,
as the comet approaches the Sun, water evaporates off along with other sublimed gases from the nucleus and produce the ‘coma’ around the nucleus, this is held by weak gravity.
Name the main components of a comet
Coma, Dust trail, ion tail, hydrogen cloud, nucleus
What is the dust trail?
the most prominent to the observer it is made of dust particles and gases from the interaction with radiation and pressure form the SUn
What is the ion tail
caused by ions from the solar wind, interacting with the particles of a comet to forma more coloured and straight tail
What is the hydrogen cloud
huge but very sparse envelope of neutral hydrogen
WHat is the coma
dense cloud of water, CO2, and other neutral gases sublimed from the nucleus
What is the nucleus
relatively solid and stable mostly ice and gas with a small amount of dust
What are the characteristics of the orbit of a comet
Comets orbit the Sun at a sharp incline to the ecliptic
-THey can have a prograde or retrograde motion
-Comets have high eccentricity and can be parabolic
WHat eventually happens to comets
Eventually comet will burn up, exhausting its materials and orbiting the SUn as a rock/debris
What is a short period comet
they have an origin from beyond neptune called the kuiper belt
-they have an orbital period of 10s-100s of years.
-they have low eccentricity
-prograde orbit
WHat is a long period comet
they have an origin within the Oort cloud (further than kuiper)
-they have an orbital period of thousands to millions of years
-they have high eccentricity
-prograde OR retrograde motion
-They rarely enter the planetary region
What is the heliosphere
An extended feature of the Sun’s influence, it is a bubble surrounding the solar system created by solar wind. Has a cigar shape due to Sun’s movement.
WHat is the Oort cloud
a theoretical spherical region around 10,000AU-20,000AU
-consists of long period comets and can be disturbed by other Stars (not our Sun)
How can you deduce the orbit of a comet using its trajectory around the Sun
If the comet travels at a velocity of elss than the escape velocity required to leave the solar system, it will have an elliptical orbit around the Sun
>Comets travelling through the escape velocity can be captured by the Sun or thrown out of orbit by its gravitational pull, giving a parabolic orbit
What can a comet be described as simply
a dirty snowball
What is a meteoroid
a fragment of a comet or asteroid which is travelling in space
What is a meteor
meteoroids that have entered the atmosphere, and burn up dues to friction with large particles in the atmosphere
-these are commonly known as shooting stars
What is a meteorite
meteors that survive their journey through the atmosphere and end up on Earth’s surface
How did Halley find the AU?
> Halley measured the times of the ingress and the egress of the transit of Venus across the Sun, from Northern and Southern locations on Earth
The observation of the path of transit in the South will be higher than the Northern observation
Therefore, two chords across the Sun’s face will have different lengths, he sued the different times for transit to find the different in length.
Then Halley used trigonometric ratios and Kepler’s laws to find the value of 1AU
The person on the South Pole will see Venus following a slightly higher path shifted North.
This is because the Sun is seen as a circle, the two points having a different length
Why do we use telescopes?
Our eyes have limited sensitivity and a tiny aperture
Name 2 theories for water on Earth
Condensation theory
Comet delivery thoery
Explain condensation theory for water on Earth
-Water was part of the Earths composition when is was first formed as the Earth cooled down, water leaked out of the rocks and condensed to form water
Explain the comet delivery theory for water on Earth
-In the early stages of the Earth’s evolution it was heavily bombarded with comets, which contain ice, the ice melted away to form the water we know today
What were galileo’s 4 major discoveries leading to teh helio-centric model
-Jupiter has 4 moons, meaning that not everything orbits the Sun
-The phases of Venus could not happen if Venus orbited Earth, there must be light incidents on different sides due to heliocentricity
-Moon has uneven craters and mountains
-Nature of Sunspots on SUns
What do telescopes use to gather light and enlarge the image, and focus to an image
lenses and mirrors
WHat is a refractor
uses a convex lens to capture and focus light
WHat is a reflector
use a concave lens to capture and focus light
Objective lens
collects light and brings to a focus
eyepiece
magnifies image for observer
resolution
detail able to be seen, the wider the objective the better the resolution
aperture
diameter of the objective element (lens of mirror)
-the larger the aperture, the more light enters the scope, therefore the image is brighter
Why are our eyes not suited for solar observations
The small aperture of the pupil and the limited sensitivity of the retina in low light gives us limited ability to make detailed astronomical observations
Newtonian Reflector
-collects light and reflects it offa concave mirror to a secondary mirror
-this is at 45 degrees to reflect light towards the eye piece lens
-the eyepiece is convex and enlarges the image
Cassegrain Reflector
-uses a concave mirror at the end of the barrel to reflect light towards the secondary mirror
-a convex mirror facing the primary mirror, which reflects light towards an eyepiece
-through a hole in the centre of the primary mirror
Galilean Refractor
-convex primary lens
-this concentrates parallel light rays towards a focal point
-the eyepiece is concave, this makes rays parallel when entering the eyes, this then magnifies the image
-typically fixed focus with a limited field of view
Keplerian Refractor
-uses two convex lenses to achieve the same effect as Galilean
-the telescope is heavier
-they are focussable
-the image produced is inverted
light grasp of a telescope..
is directly proportional to the area of the objective element.
THerefore the square of the diameter of the objective element
How can light grasp be used to compare telescopes
USing the inverse square law.
A 160mm telescope collects 4x more light than a 80mm.
160^2 = 25600
80^2 = 6400
25600/6400 = 4
