The Night Sky, Earth, Sun and Moon Flashcards Preview

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Flashcards in The Night Sky, Earth, Sun and Moon Deck (28):

How do we measure brightness in the sky?

Measure brightness in the night sky using "magnitude scale" - the more minus the brighter it is.


What are meteor showers?

Caused by the Earth ploughing through dust and particulars leftover by comets:
Perseids (August)
Leonids (Nov)
Geminids (Dec)


What are constellations?

Europeans use the standard developed by Ancient Greeks and helps us navigate the night sky.

The Plough (aka Ursa Major) or 'The Great Bear' - the front of the plough points upwards to the North Star (aka Polaris)


What is Polaris?

The North Star.


What is the "belt of venus"?

In the evening in the East you can see the shadow of the Earth and above it is pink/red light called "belt of venus".


Why is the sky blue?

"Blue light bends best" which is why sun appears red in evening (combined with the amount of air you are viewing the sun through as 10 times more air at sunset which increases the impact of light scattering).


Who first observed the planets & stars?

The ancients.


How many constellations are there?



How many stars can we see from Earth with the naked eye?

Approximately 1,500.


How was the Moon formed?

The moon is quite large in relation to the Earth in comparison to the other moons and their parent planets within the solar system.

Collision Theory: Planets collided and the material leftover formed the moon around the Earth - the Earth's gravity is not strong enought to have captured a wandering moon in its present form.


How long does it take for the Moon to orbit the Earth?

28 days to orbit the Earth = Moonth = Month

ACTUALLY the Moon does not orbit the Earth. They orbit each other around a "Barycenter" balance point (the Barycentre is the orbit around the Sun).

The moon's orbit is eliptical.


What is the average surface temperature on the Moon?

Approximately -18 degrees.


What is the tilt of the Earth?

The tilt (23.5degs) of the Earth creates the seasons.

Nothing to do with distance between the Earth and the Sun.


What is special about the Earth's orbit around the Sun?

Orbit is not completely circular - we are closer to the sun in January (Perihelon) and further away in July (Aphelion).

They orbit each other around a "Barycenter" balance point (the Barycentre is the orbit around the Sun).


What creates the tides?

The gravity from the Moon creates the tides.

The moon's gravity will pull the water (as well as the ground by up to 10cm!). Tides on both sides as the water and Earth is pulled towards the Moon a 'bulge' of water is left on other side of planet as well causing high-tide on both sides.


What does the Earth's magnetic field do?

Captures the corona mass ejections from the sun and feeds it into the north and south poles.

This causes the "northern" lights.


What is an Annular Solar Eclipse?

Annular Solar Eclipse is when the Moon is further away from the Earth causing the Sun to be seen around the edge.


What is a lunar eclipse?

When the Earth passes in front of the Sun the moon disappears into the shadow of the Earth causing a lunar eclipse.


What are the phases of the moon?

After the new moon, the sunlit portion is increasing, but less than half, so it is waxing crescent.

After the first quarter, the sunlit portion is still increasing, but now it is more than half, so it is waxing gibbous.

After the full moon (maximum illumination), the light continually decreases.

So the waning gibbous phase occurs next.

Following the third quarter is the waning crescent, which wanes until the light is completely gone -- a new moon.


What is a solar eclipse?

Due to the 5deg tilt of the moon it causes a solar eclispe a couple of times per year but this only viewable in a narrow region on Earth (the umbra shadow).

The rest of the year the moon will pass above or below the Sun.


What is Pangaea?

Pangaea - original one land mass which slowly seperated into distinctive land masses.

This is caused by seafloor spreading / seafloor subduction at the boundaries of the major tectonic plates - this movement causes earthquakes. The magnitude scale goes up in 10x i.e. 4 is 10x stronger than 3.


What is Perihelion and Aphelion?

Earth's orbit is not completely circular - we are closer to the sun in January (Perihelon) and further away in July (Aphelion).


What is Global Warming?

Global warming has increased by 0.5deg in last 100yrs. 30% increase in atmospheric carbon dioxide. Deforestation is removing the ability for the Earth to regulate these levels.


What is the Earth's average surface temperature?

15 degrees.


What was the first element to be discovered in the Sun?


However, Hydrogen is the most abundant.


What is a barycentre?

The planets actually orbit a barycentre of the solar system in a dance with the Sun. Currently in 2014 the balance point is near the middle of the Sun but by 2022 it will be well outside the Sun. The Sun orbits around this barycentre as do all the planets.


Apart from the Sun how close is our nearest star?

Red Dwarf Proxima Centauri = 4.24 light-years away.

The Solar System Alpha Centauri is located in the Centaurus constellation, which is only visible in the Southern Hemisphere, however Proxima Centauri is not visible.


What is a rogue planet?

Rogue planets are homeless worlds. They have neither sunrises nor sunsets, because unlike the planets we're more familiar with, these lonely worlds aren't tethered to a star. Instead, they travel in solitary arcs around the Milky Way's core.