Understanding Lunar and Solar Eclipses

What condition is necessary for a lunar eclipse to occur?

What is the 'line of nodes' in the context of lunar and solar eclipses?

During which phases of the Moon are eclipses possible?

What causes the precession of the Moon's orbit?

Approximately how long does each eclipse season last?

What key aspect of the Saros cycle complicates the prediction of eclipse locations?

How often do eclipse seasons occur?

How long does it take for the line of nodes to make one full rotation due to precession?

When does a lunar eclipse occur?

Why don't we see an eclipse at every full moon or new moon?

What is the arrangement of the Sun, Moon, and Earth during a new moon?

In which condition will the moon appear fully illuminated from Earth?

In the example of using a hand in a dark room to demonstrate moon phases, what does the new moon represent?

How can one predict an eclipse without sophisticated equipment?

What causes the shadows during most full moons or new moons to miss the Moon or Earth?

Lunar and Solar Eclipses

An eclipse occurs when the Moon is in Earth's shadow or the Sun is blocked by the Moon, and can only happen during a full moon or a new moon.

Types of Eclipses

A lunar eclipse occurs during a full moon, when the Earth is between the Sun and the Moon, casting a shadow on the Moon.
A solar eclipse occurs during a new moon, when the Moon is between the Sun and the Earth, blocking the Sun's light.

Orbits and Nodes

The Moon's orbit is inclined by a few degrees to the Earth's orbital plane, which is why eclipses don't occur every full moon or new moon.
The points where the Moon's orbit passes through the plane of Earth's orbit are called nodes.
The imaginary line that connects the two nodes of the Moon's orbit around Earth is called the line of nodes.
Eclipses can only occur when the Moon passes through the plane of Earth's orbit, which is when the line of nodes points towards the Sun.

Eclipse Season

The line of nodes points at the Sun during the eclipse seasons, which are the times when eclipses of the Moon and Sun are possible.
Eclipse seasons last for about a month and occur every six months, but do not occur at the same time every year due to the Moon's orbit precessing.

The Saros Cycle

The Saros cycle is an 18 year, 11 and one-third day cycle and pattern of solar and lunar eclipses.
The pattern of eclipses repeats in a cyclical manner because the Moon, nodes, and Sun return to the same arrangement as when the Saros first began.
The Saros cycle can be used to predict future eclipses, so long as records and dates of previous eclipses are available.

Learn about the spectacular phenomenon of lunar and solar eclipses, how they occur, and how ancient people predicted them without sophisticated equipment.