Moonrise Moment

Surface glossary

What is a lunar ray system?

Ray System is bright streaks of material thrown outward from a relatively young impact crater.

A detailed lunar surface showing craters, dark maria, regolith, and a rille.
A visual guide to ray system. Original Moonrise Moment illustration.

What it means

Ray System describes the Moon's landscape or the way we divide its visible surface. With no active weather to erase features quickly, much of the lunar surface preserves a long record of impacts and ancient volcanism. Changing light near the terminator often makes these features easiest to recognize from Earth.

Keep exploring

Surface Dark Side of the Moon

An informal and misleading phrase often used for the lunar far side. Both the near side and far side receive sunlight over a lunar month.

 Surface Far Side

The lunar hemisphere that faces away from Earth most of the time. It is not permanently dark.

 Surface Impact Basin

A very large impact depression. Many lunar basins were later flooded by basaltic lava and became maria.

 Surface Impact Crater

A depression formed when an asteroid, meteoroid, or comet strikes the Moon's surface.

Sources and further reading

This definition was written in plain language and checked against these science references.

Moonrise Moment showing the live direction and countdown screen.

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