Occultation

occultedlunar occultationoccultsoccultingstellar occultationoccultasteroid occultationoccultationsoccultation eventsocclusion
For the Shia Islamic belief, see the Occultation.wikipedia
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Aldebaran

Alpha Tauribrightest starRohini
Occultations of Aldebaran are in this epoch only possible by the Moon, because the planets pass Aldebaran to the north.
Aldebaran is 5.47 degrees south of the ecliptic and so can be occulted by the Moon.

Regulus

Alpha LeonisRegulus Astar
Three first magnitude stars appear well within that band – Regulus, Spica and Antares - meaning they may be occulted by the Moon and/or by planets.
Regulus is 0.465 degrees from the ecliptic, the closest of the bright stars, and is regularly occulted by the Moon.

Spica

α VirAzimechAlaezel
Three first magnitude stars appear well within that band – Regulus, Spica and Antares - meaning they may be occulted by the Moon and/or by planets.
Spica is 2.06 degrees from the ecliptic and can be occulted by the Moon and sometimes by planets.

Moon

lunarthe MoonLuna
The term occultation is most frequently used to describe those relatively frequent occasions when the Moon passes in front of a star during the course of its orbital motion around the Earth.
Because the Moon is continuously blocking our view of a half-degree-wide circular area of the sky, the related phenomenon of occultation occurs when a bright star or planet passes behind the Moon and is occulted: hidden from view.

Quasar

quasarsquasi-stellar objectQSO
This was crucial for the unambiguous identification of the radio source 3C 273 with the optical quasar and its jet, and a fundamental prerequisite for Maarten Schmidt's discovery of the cosmological nature of quasars.
Another radio source, 3C 273, was predicted to undergo five occultations by the Moon.

Minor-planet moon

moonasteroid moonbinary
In addition, mutual occultation and eclipsing events can occur between a minor planet and its satellite. A large number of these minor-planet moons have been discovered analyzing the photometric light curves of rotating minor planets 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.
The first modern era mention of the possibility of an asteroid satellite was in connection with an occultation of the bright star Gamma Ceti by the asteroid 6 Hebe in 1977.

3C 273

3C2733C 273 quasar
This was crucial for the unambiguous identification of the radio source 3C 273 with the optical quasar and its jet, and a fundamental prerequisite for Maarten Schmidt's discovery of the cosmological nature of quasars.
After accurate positions were obtained using lunar occultation by Cyril Hazard at the Parkes Radio Telescope,

Antares

Antares Bα ScorpionisAlpha Scorpii
Three first magnitude stars appear well within that band – Regulus, Spica and Antares - meaning they may be occulted by the Moon and/or by planets.
Antares is 4.57 degrees south of the ecliptic, one of four first magnitude stars within 6° of the ecliptic (the others are Spica, Regulus and Aldebaran), so it can be occulted by the Moon.

Star

starsstellarmassive star
The term occultation is most frequently used to describe those relatively frequent occasions when the Moon passes in front of a star during the course of its orbital motion around the Earth.
Another technique for measuring the angular size of stars is through occultation.

Light curve

lightcurvelight-curvelight curves
A large number of these minor-planet moons have been discovered analyzing the photometric light curves of rotating minor planets 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.
Light curves can be periodic, as in the case of eclipsing binaries, Cepheid variables, other periodic variables, and transiting extrasolar planets, or aperiodic, like the light curve of a nova, a cataclysmic variable star, a supernova or a microlensing event or binary as observed during occultation events.

Atmospheric sounding

soundingsoundingsAtmospheric sounder
Pluto occulted stars in 1988, 2002, and 2006, allowing its tenuous atmosphere to be studied via atmospheric limb sounding.
It does this in one of two ways: either it tracks the sun, moon, a star, or another transmitting satellite through the limb as the source gets occultated behind the Earth, or it looks towards empty space, collecting radiation that is scattered from one of these sources.

20000 Varuna

Varuna2000 Varunasuggested
Occultations have also been used to estimate the diameter of trans-Neptunian objects such as, Ixion, and Varuna.
Observations of stellar occultations by Varuna have also provided varying size estimates.

2 Pallas

Pallasasteroid Pallas(2) Pallas
Pallas has been observed occulting stars several times, including the best observed of all asteroid occultation events on 29 May 1983, when careful occultation timing measurements were taken by 140 observers.

Uranus

Uranian34 TauriMagnetosphere of Uranus
Uranus's rings were first discovered when that planet occulted a star in 1977.
The discovery was serendipitous; they planned to use the occultation of the star SAO 158687 (also known as HD 128598) by Uranus to study its atmosphere.

Eris (dwarf planet)

Eris136199 Eris2003 UB313
Observations of a stellar occultation by Eris in 2010 showed that its diameter was 2326 ±, very slightly less than Pluto, which was measured by New Horizons as 2376.6 ± in July 2015.

Trans-Neptunian object

TNOtrans-Neptunian objectscolor indices
Occultations have also been used to estimate the diameter of trans-Neptunian objects such as, Ixion, and Varuna.
For very large objects, with very well known orbital elements (like Pluto), diameters can be precisely measured by occultation of stars.

704 Interamnia

Interamnia
An occultation in 1996 produced a diameter of 329 km.

94 Aurora

Aurora
Observations of an occultation using nine chords indicate an oval outline of 225×173 km.

Saturn

Atmosphere of SaturnOrbit of SaturnPhainon
On 3 July 1989, Saturn passed in front of the 5th magnitude star 28 Sagittarii.
From time to time Saturn is occulted by the Moon (that is, the Moon covers up Saturn in the sky).

39 Laetitia

Laetitia
Observations of an occultation on March 21, 1998, produced several chords indicating an ellipsoidal cross-section of 219 × 142 km.

48 Doris

Doris
An occultation on March 19, 1981, suggested a diameter of 219±25 km.

Transit (astronomy)

transittransitingtransits
Cases where the nearer object appears larger and completely hides the more distant object are known as occultations.

444 Gyptis

Gyptis
Observations of an occultation on October 14, 2007, produced six chords indicating a cross-section ellipsoid of 179×150 km.

163 Erigone

Erigone
In the early morning hours of March 20, 2014, Erigone occulted the first-magnitude star Regulus as first predicted by A. Vitagliano in 2004.

486958 Arrokoth

ArrokothPT1Snowman (asteroid)
Prior to the New Horizons flyby of Arrokoth, stellar occultations by Arrokoth had provided evidence for its bilobate shape.