- A process of erosion where water leaks to the surface through the
pores of rocks; as the water flows away, it slowly removes material to form
valleys and channel networks.
- A body that revolves around a larger body.
- A line of cliffs produced by faulting or erosion;
a relatively straight, clifflike face or slope of considerable linear
extent, breaking the general continuity of the land by separating surfaces
lying at different levels.
- A lobate or irregular scarp.
- One-half of the longest dimension of an ellipse.
- Striated conical fracture surfaces produced by meteorite impact
into fine-grained, brittle rocks such as limestone.
- A satellite that constrains the extent of a planetary ring
through gravitational forces.
- Any of several extensive regions where ancient
Precambrian crystalline rocks are exposed at
the Earth's surface.
- A volcano in the shape of a flattened dome, broad and low, built
by flows of very fluid lava.
- The production of irreversible chemical or physical changes in
rocks by a shock wave generated by impact, or detonation of
high-explosive or nuclear devices.
- Of, relating to, or expressed in relation to stars or constellations.
- Rotation time measured with respect to the fixed stars rather than
the Sun or body orbited.
- This phrase literally means iron-loving elements. It includes Iridium, Osmium, Platinum and Plladium, which are found in the metal-rich interiors of chemically segregated asteroids and planets; consequently, these
elements are extremely rare on Earth's surface.
- A rock or mineral whose structure is dominated by bonds of
silicon and oxygen atoms (ie. olivine).
- A bay.
- The approximately 11-year, quasi-periodic variation in the frequency or
number of solar active events.
- The large cloud of gas and dust from which the
Sun and planets condensed 4.6 billion years ago.
- A tenuous flow of gas and energetic charged particles, mostly
protons and electrons -- plasma -- which stream
from the Sun; typical solar wind velocities are almost 350 kilometers (217 miles)
- A low, steep-sided cone built up from fluid pyroclasts coating the
surface around a vent.
- A device that measures the amount of reflected or radiated energy
from a surface in two or more wavelengths.
- The distribution of wavelengths and frequencies.
speed of light
- Light speed equals 299,792,458 meters/second (186,000 miles/second).
of Relativity implies that nothing can go faster
than the speed of light.
- The grass-like patterns of gas seen in the solar atmosphere.
- The cold region of a planetary atmosphere above the
convecting regions (the
troposphere), usually without vertical motions
but sometimes exhibiting strong horizontal jet streams.
- A dense, high-pressure phase of quartz that has so far been
identified only in shock-metamorphosed, quartz-bearing rocks from
meteorite impact craters.
- The process of one lithospheric plate descending beneath another.
- Sublimation occurs when a substance changes directly from a solid to a gas without becoming liquid.
- Subparallel furrows and ridges.
- A heavy, corrosive, oily, dibasic strong acid H2SO4 that is colorless
when pure; it is a vigorous oxidizing and dehydrating agent.
- An area seen as a dark spot on the
photosphere of the Sun. Sunspots are
concentrations of magnetic flux, typically occurring in
bipolar clusters or groups. They appear dark because they are cooler than
the surrounding photosphere.
- The planets Mars, Jupiter, Saturn, Uranus, Neptune and Pluto
are superior planets because their
orbits are farther from the Sun than Earth's orbit.
synchronous orbit radius
- The orbital radius at which the satellite's orbital period is equal to the
rotational period of the planet. A synchronous satellite with an
orbital inclination of zero (same plane as the planet's equator)
stays fixed in the sky from the perspective of an observer on the
planet's surface. These orbits are commonly used for communications
- A satellite's rotational period is equal to its orbital period;
this causes the same side of a satellite to always face the planet.
Synchronous rotation occurs when a planet's gravity produces a tidal
bulge in its satellite. The gravitational attraction and bulge acts like a torque,
which slows down the satellite until it reaches a synchronous rotation.
- SAR is a side-looking imaging system that uses the
Doppler effect to sharpen the effective
resolution in the cross-track direction.