Astronomy Test Study Guide

How long of a time is it from New to full moon?

29.5 days

What is the shape of the moon's orbit

Elliptical orbit

What are the positions of the earth,moon,and sun during an eclipse?

The earth comes in between the sun and the moon

Why does a new phase occur every month but a lunar eclipse occurs on,y twice a year?

During a lunar eclipse, Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon. Earth's shadow covers all or part of the lunar surface,

What is a magnetosphere and why is it important?

Earth's magnetosphere is a bit like a magnetic force field that surrounds our planet. The magnetosphere protects our planet from some types of radiation from the Sun.

How can you use the number of craters to determine the ge of a planet's or moon's surface?

counting the number of impact craters. This technique works because the rate at which impacts have occurred in the solar system has been roughly constant for several billion years.

What is regolith?

the layer of unconsolidated rocky material covering bedrock.

What do the mare look like on the moon and why are they so smooth?

large, dark, basaltic plains, Because there is no atmosphere or water on the Moon, there has been no wind, water, or ice to carve them into cliffs and sharp peaks, the way we have seen them shaped on Earth. Their smooth features are attributed to gradual erosion, mostly due to impact cratering from meteorites.

What are the moon phases ?

new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent

Why do we not have eclipses every month?

the orbit of the moon is tilted relative to the orbit of the Earth around the sun, so the moon often passes below or above Earth.

What are apogee and perigee?

Apogee is farthest from the earth and perigee is closest to the earth

What are the two parts of a shadow and in which part is the Sun partially visible?

Penumbra and umbra, sun is partially visible in the penumbra

What are the moon's mantle and core like compared to Earth?

The Moon does have layers, much like the Earth, in fact -- except that compared with the Earth, the Moon has a lot more rocky mantle and a lot less metallic core.

What cool things can you see during a total eclipse?

The Sun is now completely hidden, revealing the full glory of the solar corona

In what ways is the giant impact theory better at explaining the formation of the moon than other formation theories

The prevailing theory supported by the scientific community, the giant impact hypothesis suggests that the moon formed when an object smashed into early Earth. Like the other planets, Earth formed from the leftover cloud of dust and gas orbiting the young sun.

The lunar highlands have about ten times more craters on a given area than do the Maria. What does this imply?

The radioactive dating of highland samples shows that they are only slightly older than the maria, about 4.2 billion years versus 3.8 billion years.

What is a saros cycle?

The roughly 18-year cycle over which the pattern of eclipses repeats

What are Bailey's Beads?

When little points of light reflect off the craters of the moon during an eclipse

The Earth's shadow on the moon is curved. Why?

When the Sun moves forward or backwards from this postion more or less of the bit of the Moon that can be seen from the Earth will be lit up and the shadow will now be curved.

About how far way is the moon?

238,900 miles

Why does the moon not have erosion?

Because it has no atmosphere

Why is the path of totality of a solar eclipse different each time?

Because of the relative sizes of the moon and sun and their relative distances from Earth, the path of totality is usually very narrow

Why does the moon turn orange-red during a total lunar eclipse?

It's called Rayleigh scattering. Light travels in waves, and different colours of light have different physical properties.

How is the moon's geology different from Earth's?

Moon (impact craters and basins, lava flows and related features, and tectonic scarps and ridges) all formed predominantly in the first half of the solar system's history.

What is an annular eclipse? Why does it happen?

Occurs when the moon passes completely in front of the sun •However, the moon's angular diameter is less than that of the sun •Because the moon moves in an elliptical orbit •Its angular diameter gets bigger and smaller

What missions went to the moon? What did they encounter?

Six missions landed humans on the Moon, beginning with Apollo 11 in July 1969, during which Neil Armstrong became the first person to walk on the Moon. Apollo 13 was intended to land; however, it was restricted to a flyby due to a malfunction aboard the spacecraft. All nine crewed missions returned safely to the Earth.

What is the path of totality?

The path traced on the Earth's surface by the moon's shadow (more precisely, the umbra) during a total eclipse of the sun.

How big is the moon compared to Earth?

The moon is 1/4 the size of Earth.

What can we learn from lunar rock samples?

The shape, size, arrangement and composition of the individual grains and crystals in a rock tell us about its history. Radioactive clocks tell us the age of the rock. Tiny tracks even tell us the radiation history of the Sun during the last 100,000 years.

What's the difference between umbra and penumbra?

Umbra is the dark part in between and penumbra is the light part that surrounds the umbra

The moon is low in the western sky at sunrise, what is its phase?

Waning crescent, meaning a full moon stage

Why does the moon have phases?

We only see one side of the moon •Half of the moon's surface is illuminated at all times •There is no "dark side" of the moon How much of the illuminated side we see depends on the moon's position •We can see anywhere from 0% to 100% of the illuminated surface •The phase is determined by •The amount we see, and... •whether it's getting bigger or smaller