Ch 28 Tools of Astronomy

Ecliptic is the plane in which Earth orbits about the Sun. is the plane in which Earth orbits about the Sun.

Perigee is the closest point in the Moon’s orbit to Earth. is the closest point in the Moon’s orbit to Earth.

is the farthest point in the Moon’s orbit from Earth. is the farthest point in the Moon’s orbit from Earth. Apogee

Albedo the amount of sunlight that its surface reflects the amount of sunlight that its surface reflects – The Moon is only about 0.07 (7 percent) – Earth’s average of 0.31 (31 percent).

Regolith is a layer of loose, ground-up rock on the surface of the Moon that formed as a result of the heavy bombardment during its first 800 million years. is a layer of loose, ground-up rock on the surface of the Moon that formed as a result of the heavy bombardment during its first 800 million years.

Highland are lunar regions that are light in color, mountainous, and heavily covered with craters. are lunar regions that are light in color, mountainous, and heavily covered with craters.

Mare (plural, Maria) are lunar regions that are dark, smooth plains, which on average are 3 km lower in elevation than the highlands. are lunar regions that are dark, smooth plains, which on average are 3 km lower in elevation than the highlands.

Impact Crater were formed when objects from space crashed into the lunar surface. were formed when objects from space crashed into the lunar surface.

Ejecta is material blasted out during impacts that fell back to the surface. is material blasted out during impacts that fell back to the surface.

Rilles are meandering, valleylike structures that are found in the Maria. are meandering, valleylike structures that are found in the Maria.

Summer Solstice – occurs around June 21 each year when the Sun is directly overhead at the Tropic of Cancer, which is at 23.5° N.

Winter Solstice – occurs around December 21 each year when the Sun is directly overhead at the Tropic of Capricorn which is at 23.5° S.

Autumnal Equinox – occurs around September 21, halfway between the summer and the winter solstices when the Sun is directly over the equator.

Vernal Equinox – occurs around March 21, halfway between the winter and the summer solstices when the Sun is directly over the equator.

Synchronous Rotation – is the state at which orbital and rotational periods are equal. – As the Moon orbits Earth, the same side faces Earth at all times because the Moon has a synchronous rotation, spinning exactly once each time it goes around Earth.

Solar Eclipse occurs when the Moon passes directly between the Sun and Earth and blocks our view of the Sun. occurs when the Moon passes directly between the Sun and Earth and blocks our view of the Sun.

Lunar Eclipse occurs when the full Moon passes through Earth’s shadow. occurs when the full Moon passes through Earth’s shadow.

Interferometry – the process of linking separate telescopes together so that they act as one telescope.

Spinoff – technologies that were originally developed for use in space programs that have been passed on to commercial industries for common use.

Refracting Telescope refractors, are telescopes that use lenses to bring visible light to a focus. refractors, are telescopes that use lenses to bring visible light to a focus.

Reflecting Telescope reflectors, are telescopes that bring visible light to a focus with mirrors. reflectors, are telescopes that bring visible light to a focus with mirrors.

Ray are long trails of ejecta that radiate outward from some craters. are long trails of ejecta that radiate outward from some craters.