Occultation

Both transit and occultation may be referred to generally as occlusion; and if a shadow is cast onto the observer, it is called an eclipse.

[1] Three first magnitude stars appear well within that band – Regulus, Spica, and Antares – meaning they may be occulted by the Moon or by planets.

Photoelectric analysis of lunar occultations have also discovered some stars to be very close visual or spectroscopic binaries.

[5] If the nearer planet appears larger than the more distant one, the event is called a mutual planetary occultation.

This event is visible worldwide since the duo would be positioned almost in opposition to the sun, in the border line between the constellations of Orion and Taurus.

[7] A further set of occultations are those when a small Solar System body or dwarf planet passes in front of a star, temporarily blocking its light as seen from Earth.

Software for coordinating observations is available for download at http://www.occultwatcher.net/ In addition, mutual occultation and eclipsing events can occur between a primary and its satellite.

A large number of moons have been discovered analyzing the photometric light curves of small bodies and detecting a second, superimposed brightness variation, from which an orbital period for the satellite (secondary), and a secondary-to-primary diameter-ratio (for the binary system) can often be derived.

Because of its relatively large angular diameter the Moon, at any given time, occults an indeterminate number of stars and galaxies.

The satellite consists of a large, very lightweight sheet, and a set of maneuvering thrusters and navigation systems.

The second would place the satellite in a highly elliptical orbit about the Earth, and work in conjunction with a ground telescope.

At the apogee of the orbit, the satellite would remain relatively stationary with respect to the ground, allowing longer exposure times.