Topic 5 Flashcards
Why can’t you look directly at the sun?
- would burn retina
-Causes permanent blindness
Name a way to safely observe the sun
-Telescopic projection
-H-alpha filter
-Pinhole camera
What is the ecliptic?
> The path a planet takes in its orbit around a star.
- this is an imaginary plane between the Earth & Sun.
Do all planets follow the ecliptic exactly?
Not all planets follow this line :
- most move a degree or two either side, called the inclination
What is a superior planet? Name them
Planets that have an orbit outside of ours
(Mars, Jupiter, Saturn, Uranus, Neptune)
What is an inferior planet? Name them.
Planets with an orbit inside of ours (Mercury, Venus)
What find of motion do superior planets typically have?
Direct/prograde motion across the sky
- this means right→ left or east → west
What is an inferior planet also known as?
Conjunction
What type of motion to superior planets usually have across the sky?
direct/ prograde motion
-this means left-> right or east->west
What is a stationery point
When a planet does not appear to move in the sky for a few nights
What is retrograde motion
The apparent motion of a planet in a direction opposite to that of other bodies within its system, observed from a particular vantage point
Why does retrograde motion happen?
The Earth is nearer to the Sun and has a smaller orbit
-The planet appears to move normally but then Earth catches up.
-When they are aligned the planet may seem to stay still
-The planet then appears to move backwards as he Earth moves in front
-Eventually the planets realign
What is the First Point of Area
THe point at which the SUn on the ecliptic crosses the celestial equator at the vernal equinox
What is the FPA named after
The constellation where the Sun on the ecliptic first crossed the celestial equator at the vernal equinox many years ago
What is the First Point of Libra
The point where the sun on the ecliptic crosses the equator at the autumnal equinox
What is a meteor
Fragments of dust from comets or asteroids that Earth smashes into as it orbits the Sun, on Earth we see shooting stars
How are meteor showers named
Named after the particular constellation they appear to diverge from
What is the point meteors seem to come from
radiant
Are meteors parallel to each other
YES
What is opposition
When a planet is opposite the Earth from the Sun
What is opposition good for
-Best time to observe planets, particularly superior planets
What is transit
The passing of one body in front of another in celestial line, will cross disc of Sun
- an eclipse is this
What is occultation
More dramatic that a transit where a celestial body observes and covers another
-an eclipse is this
What is elongation
An inferior planet cannot be seen in opposition
The best position for viewing is position forming 90 degrees between the SUn and Earth
The remaining angle is the angle of elongation
