Chapter 16: Earth in Space

Fill-in-the-blank practice flashcards covering Earth's shape, motions, coordinate systems, calendar time, and the Earth-Moon system from Chapter 16 of Physical Science.

According to the proto-planet nebular theory, all planets move around the Sun in the same direction in __________ orbits.

elliptical

The flatness of the solar system results in observable planets moving in or near the plane of Earth's orbit, which is called the __________.

ecliptic plane

One of the observational reasons the ancient Greeks concluded Earth is round was that ships slowly disappear below the __________ as they sail into the distance.

horizon

The ancient Greeks reasoned that the Earth must be round because during a lunar eclipse, the shadow cast by Earth on the Moon is __________.

circular

By measuring the shadow cast by an obelisk in Alexandria, Eratosthenes calculated an angle of {7^\\bot 12'}, which corresponds to exactly __________ of a circle.

$$\frac{1}{50}\text{th}$$

Modern satellite measurements show that Earth is not a perfect sphere but an __________, which bulges at its center.

oblate spheroid

Earth rotates on its axis at a speed of approximately __________ at the Equator.

$$1670\,\text{km/h}\text{ (}1040\,\text{mi/h)}$$

The three motions of Earth that are independent of the Sun and galaxy are rotation, revolution, and __________.

precession

Precession is the slow reorienting of Earth's axis that completes one full cycle every __________.

$$26,000\text{ years}$$

In its elliptical orbit around the Sun, Earth moves fastest at __________ and slowest at aphelion.

perihelion

Because Earth is closer to the Sun in January than in July by approximately $\sim 5\text{ million km}$, Earth receives __________ more solar energy in January than in July.

$$6\%$$

In the Northern Hemisphere, winter occurs when Earth is __________ to the Sun.

closest

Earth's axis is tilted at an angle of __________ to the ecliptic plane.

$$23.5^\circ$$

The summer solstice occurs on June 21 or 22 in the Northern Hemisphere, when the Sun at noon reaches its __________ altitude of the year.

highest

During the spring equinox on March 21 and autumnal equinox on September 23, Earth's axis is __________ to the Sun.

perpendicular

In 1851, French physicist __________ proved that Earth rotates by observing the changing plane of a long, heavy pendulum.

Jean Foucault

At the North Pole, a Foucault pendulum completes one full apparent turn in about __________.

$$24\text{ h}$$

Due to axial precession, the North celestial pole will point toward the star __________ around the year 14,000 AD.

Vega

The Prime Meridian has a longitude of $0^\circ 0' 0"$ and passes through the observatory in __________, England.

Greenwich

The parallel located at $23.5^\circ\text{N}$ is called the __________.

Tropic of Cancer

A sidereal day, which is the interval between two consecutive crossings of the celestial meridian by a star, lasts __________.

$$23\text{ h } 56\text{ min } 4\text{ s}$$

Because the Earth rotates $360^\circ$ in 24 hours, each standard time zone spans approximately __________ of longitude.

$$15^\circ$$

Introduced in 1582 CE by Pope Gregory XIII, the __________ dropped leap-year days from century years not divisible by 400 to correct Julian calendar drift.

Gregorian calendar

The lunar highlands consist of light-colored rocks called __________, whereas the smooth lunar maria consist of basalts.

breccias

The Moon's surface is covered with a fine, glassy dust produced by meteorite impacts, known as __________.

regolith

We only ever see one side of the Moon from Earth because the Moon's period of rotation equals its period of __________.

revolution around the Earth

During a solar eclipse, observers located within the Moon's __________ experience a total eclipse.

umbra

The greatest tidal ranges occur during full moon and new moon phases and are known as __________.

spring tides

Tides that produce the lowest tidal change when the Sun and Moon are at right angles during quarter moon phases are called __________.

neap tides

The greatest tidal change in the world occurs in the __________, reaching variations up to $50\text{ feet}$.

Bay of Fundy