Chapter 17- Physical Science

Highlands

Light-colored rock surface of the Moon that is older, more cratered, and extends to several kilometers above the average elevation on the Moon.

Maria

Large, dark, flat areas on the Moon believed to be craters formed by large impacts from space that then filled with volcanic lava.

Crater

A circular depression on the surface of the Moon caused by the impact of a meteoroid.

Synodic Month (Rotational Period)

The time it takes the Moon to go through one complete cycle of phases (a month of phases), 29.5 days.

Sidereal Month (Orbital Period)

The time it takes for the Moon to make one complete cycle relative to the stars, 27.3 days.

New Moon

The phase of the Moon that occurs when the Moon is on the same meridian as the Sun at 12 noon local solar time.

Crescent Moon

The Moon viewed when less than one-half of its observed surface is illuminated.

Gibbous Moon

The Moon viewed when more than one-half of its illuminated surface is observed from the Earth.

First-Quarter Phase

The Moon when it is 90 degrees east of the Sun and appears as a quarter moon on an observer’s meridian at 6 p.m. local solar time.

Full Moon

The phase of the Moon that occurs when the Moon is 180 degrees east of the Sun and appears on the observer’s meridian at 12 midnight local solar time.

Last-Quarter Phase

The phase that occurs when the Moon is 270 degrees east of the Sun and appears on the observer’s meridian at 6 a.m. local solar time.

Eclipse

The blocking of the light of one celestial body by another.

Umbra

A region of total darkness in a shadow. During an eclipse, an observer in the umbra sees a total eclipse.

Total Solar Eclipse

Complete blocking of the Sun, seen by an observer in the umbra; the relative positions of the Earth, Sun, and Moon are (in order from center to edge of solar system): Sun, Moon, and Earth.

Penumbra

A semidark region of the Moon’s shadow. During an eclipse, an observer in the penumbra sees only a partial eclipse.

Total Lunar Eclipse

The Earth’s umbral (dark) shadow completely covers the Moon; the relative positions of the Earth, Sun, and Moon are (in order from center to edge of solar system): Sun, Earth, and Moon.

Tides

The periodic rise and fall of the water level along the shores of large bodies of water. The Moon attracts the ocean on the side nearest it, creating a bulge. The bulge on the opposite side of the Earth that results in there being two daily high tides is caused by the Earth being pulled away from the water on the other side by the Moon.

Asteroids

Large and small chunks of matter that orbit the Sun (usually between Mars and Jupiter), sometimes called minor planets.

Meteoroids

Small, interplanetary metallic and stony objects in space before they encounter the Earth.

Meteor

A metallic or stony object that burns up as it passes through the Earth’s atmosphere and appears to be a “shooting star.”

Meteorites

A metallic or stony object from the solar system that strikes the Earth’s surface.

Comet

A relatively small object that is composed of rock, dust, and ices and that revolves about the Sun in a highly elliptical orbit.

Oort Cloud

The cloud of cometary objects believed to be orbiting the Sun far beyond the orbit of Neptune at about 50,000 astronomical units and from which the majority of comets originate.

Kuiper Belt

A doughnut-shaped ring of space around the Sun beyond the orbit of Neptune and that extends to well beyond the orbit of Pluto and Eris, containing many short-period comets.

Interplanetary Dust

Very small solid particles known as micrometeoroids that exist in the space between the planets.

Halley’s Comet reappears every____ years.

76

The Moon changes phase every ____.

7.38 solar days

The rocks brought back from the Moon are _____.

3.1 - 4.4 billion years old

If a person weighs 843 N on the Earth, what is the person's weight on the Moon?

140.5 N

If the Moon rises at 3:45 P.M. on a particular day, about what time will it rise 5 days later?

7:55 pm