Planetary transits and occultations

Last updated

In astronomy, planetary transits and occultations occur when a planet passes in front of another object, as seen by an observer. The occulted object may be a distant star, but in rare cases it may be another planet, in which case the event is called a mutual planetary occultation or mutual planetary transit, depending on the relative apparent diameters of the objects. [1]

Contents

The word "transit" refers to cases where the nearer object appears smaller than the more distant object. Cases where the nearer object appears larger and completely hides the more distant object are known as occultations.

Mutual planetary occultations and transits

Mutual occultations or transits of planets are extremely rare. The most recent event occurred on 3 January 1818, and the next will occur on 22 November 2065. Both involve the same two planets: Venus and Jupiter.

Historical observations

An occultation of Mars by Venus on 13 October 1590 was observed by the German astronomer Michael Maestlin at Heidelberg. [2] [3] The 1737 event (see list below) was observed by John Bevis at Greenwich Observatory – it is the only detailed account of a mutual planetary occultation. A transit of Mars across Jupiter on 12 September 1170 was observed by the monk Gervase at Canterbury, [4] and by Chinese astronomers. [5]

Future events

The next time a mutual planetary transit or occultation will happen (as seen from Earth) will be on 22 November 2065 at about 12:43 UTC, when Venus near superior conjunction (with an angular diameter of 10.6") will transit in front of Jupiter (with an angular diameter of 30.9"); however, this will take place only 8° west of the Sun, and will therefore not be visible to the unaided/unprotected eye. Before transiting Jupiter, Venus will occult Jupiter's moon Ganymede at around 11:24 UTC as seen from some southernmost parts of Earth. Parallax will cause actual observed times to vary by a few minutes, depending on the precise location of the observer.[ citation needed ]

List of mutual planetary occultations and transits

There are only 18 mutual planetary transits and occultations as seen from Earth between 1700 and 2200. There is a very long break of events between 1818 and 2065. [3]

A simulation of Venus transiting Jupiter, as it did on 3rd of January, 1818. Jupiter Venus transit 18180103.png
A simulation of Venus transiting Jupiter, as it did on 3rd of January, 1818.

Mutual occultations, transits, and eclipses of the moons of Jupiter and Saturn

Twice during the orbital cycles of Jupiter and Saturn, the equatorial (and satellite) planes of those planets are aligned with Earth's orbital plane, resulting in a series of mutual occultations and eclipses between the moons of these giant planets. The terms eclipse, occultation, and transit are also used to describe these events. [1] A satellite of Jupiter (for example) may be eclipsed (i.e. made dimmer because it moves into Jupiter's shadow), occulted (i.e. hidden from view because Jupiter lies on our line of sight), or may transit (i.e. pass in front of) Jupiter's disk (see also Solar eclipses on Jupiter).

Other planetary occultations

This table is another compilation of occultations and transits of bright stars and planets by solar planets.[ citation needed ] These events are not visible everywhere the occulting body and the occulted body are above the skyline. Some events are barely visible, because they take place in close proximity to the Sun.

DayTime (UT)Foreground planetBackground objectElongation
9 December 180207:36 Mercury Acrab 16.2° West
9 December 180820:34Mercury Saturn 20.3° West
22 December 181006:32 Venus Xi-2 Sagittarii 11.1° East
3 January 181821:52Venus Jupiter 16.5° West
11 July 182509:10Venus Delta-1 Tauri 44.4° West
11 July 183712:50Mercury Eta Geminorum 17.8° West
9 May 184119:35Venus 17 Tauri 9.2° East
27 September 184318:00Venus Eta Virginis 3.2° West
16 December 185011:28Mercury Lambda Sagittarii 10.2° East
22 May 185505:04Venus Epsilon Geminorum 37.4° East
30 June 185700:25 Saturn Delta Geminorum 8.4° East
5 December 186514:20MercuryLambda Sagittarii21.0° East
28 February 187605:13 Jupiter Acrab97.6° West
7 June 188120:54MercuryEpsilon Geminorum21.2° East
9 December 190617:40VenusAcrab14.9° West
27 July 191002:53VenusEta Geminorum31.0° West
24 December 193718:38MercuryOmicron Sagittarii11.6° East
10 June 194002:21MercuryEpsilon Geminorum20.1° East
25 October 194701:45Venus Zuben-el-genubi (Alpha-2 Librae) 13.5° East
7 July 195914:30Venus Regulus 44.5° East
27 September 196515:30Mercury Eta Virginis 2.6° West
13 May 197120:00JupiterBeta Scorpii (both components)169.5° West
8 April 197601:00 Mars Epsilon Geminorum81.3° East
17 November 198115:27Venus Nunki 47.0° East
19 November 198401:32VenusLambda Sagittarii39.2° East
3 July 1989Saturn28 Sagittarii
4 December 201516:14MercuryTheta Ophiuchi9.6° East
17 February 203515:19Venus Pi Sagittarii 42.1° West
1 October 204422:00VenusRegulus38.9° West
23 February 204619:24Venus Rho-1 Sagittarii 45.4° West
10 November 205207:20Mercury Zuben-el-genubi (Alpha-2 Librae) 2.8° West
22 November 206512:45VenusJupiter7.9° West
15 July 206711:56Mercury Neptune 18.4° West
11 August 206920:25VenusZavijava38.4° East
3 October 207822:00MarsTheta Ophiuchi71.4° East
11 August 207901:30Mercury Mars 11.3° West
27 October 208813:43MercuryJupiter4.7° West
7 April 209410:48MercuryJupiter1.8° West

Related Research Articles

<span class="mw-page-title-main">Eclipse</span> Astronomical event where one body is hidden by another

An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three celestial objects is known as a syzygy. An eclipse is the result of either an occultation or a transit. A "deep eclipse" is when a small astronomical object is behind a bigger one.

<span class="mw-page-title-main">Planet</span> Large, round non-stellar astronomical object

A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion.

<span class="mw-page-title-main">Solar System</span> The Sun and objects orbiting it

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main-sequence star.

<span class="mw-page-title-main">Conjunction (astronomy)</span> When two astronomical objects have the same right ascension or the same ecliptic longitude

In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.

<span class="mw-page-title-main">Astronomical transit</span> Term in astronomy

In astronomy, a transit is the passage of a celestial body directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of the larger body, covering a small portion of it.

<span class="mw-page-title-main">Occultation</span> Occlusion of an object by another object that passes between it and the observer

An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks from view (occults) an object in the background. In this general sense, occultation applies to the visual scene observed from low-flying aircraft when foreground objects obscure distant objects dynamically, as the scene changes over time.

<span class="mw-page-title-main">Extraterrestrial sky</span> Extraterrestrial view of outer space

In astronomy, an extraterrestrial sky is a view of outer space from the surface of an astronomical body other than Earth.

A triple conjunction is an astronomical event when two planets or a planet and a star appear to meet each other three times during a brief period, either in opposition or at the time of inferior conjunction, if an inferior planet is involved. The visible movement of the planet or the planets in the sky appears therefore normally prograde at the first conjunction, retrograde at the second conjunction, and again prograde at the third conjunction.

<span class="mw-page-title-main">Solar eclipses on Jupiter</span> When moons of Jupiter pass before the Sun

Solar eclipses on Jupiter occur when any of the natural satellites of Jupiter pass in front of the Sun as seen from the planet Jupiter.

<span class="mw-page-title-main">Formation and evolution of the Solar System</span> Modelling its structure and composition

There is evidence that the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

An extraterrestrial vortex is a vortex that occurs on planets and natural satellites other than Earth that have sufficient atmospheres. Most observed extraterrestrial vortices have been seen in large cyclones, or anticyclones. However, occasional dust storms have been known to produce vortices on Mars and Titan. Various spacecraft missions have recorded evidence of past and present extraterrestrial vortices. The largest extraterrestrial vortices are found on the gas giants, Jupiter and Saturn; and the ice giants, Uranus and Neptune.

A planet symbol or planetary symbol is a graphical symbol used in astrology and astronomy to represent a classical planet or one of the modern planets. The symbols were also used in alchemy to represent the metals associated with the planets, and in calendars for their associated days. Most of the symbols originated in Greco-Roman astronomy; their modern forms developed in the 16th century.

<span class="mw-page-title-main">Discovery and exploration of the Solar System</span>

Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust.

In astrology, planets have a meaning different from the astronomical understanding of what a planet is. Before the age of telescopes, the night sky was thought to consist of two similar components: fixed stars, which remained motionless in relation to each other, and moving objects/"wandering stars", which moved relative to the fixed stars over the course of the year(s).

<i>Planetary Science Decadal Survey</i> Publication of the United States National Research Council

The Planetary Science Decadal Survey is a serial publication of the United States National Research Council produced for NASA and other United States Government Agencies such as the National Science Foundation. The documents identify key questions facing planetary science and outlines recommendations for space and ground-based exploration ten years into the future. Missions to gather data to answer these big questions are described and prioritized, where appropriate. Similar decadal surveys cover astronomy and astrophysics, earth science, and heliophysics.

<span class="mw-page-title-main">Syzygy (astronomy)</span> Alignment of celestial bodies

In astronomy, a syzygy is a roughly straight-line configuration of three or more celestial bodies in a gravitational system.

<span class="mw-page-title-main">Outline of the Solar System</span> Overview of and topical guide to the Solar System

The following outline is provided as an overview of and topical guide to the Solar System:

<span class="mw-page-title-main">Historical models of the Solar System</span>

Historical models of the Solar System first appeared during prehistoric periods and are being updated to this day. The models of the Solar System throughout history were first represented in the early form of cave markings and drawings, calendars and astronomical symbols. Then books and written records became the main source of information that expressed the way the people of the time thought of the Solar System.

References

  1. 1 2 P. Kenneth Seidelmann (ed.), Explanatory Supplement to the Astronomical Almanac: A Revision to the Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac (Sausalito [CA]: University Science Books, 1992).
  2. Curtis, Jan. "Planet-on-Planet Occultations (Worldwide)" . Retrieved 2012-08-08.
  3. 1 2 Albers, Steven (March 1979). "Mutual Occultations of Planets: 1557-2230". Sky and Telescope. 57 (3): 220. Bibcode:1979S&T....57..220A.
  4. Stubbs, William (1879). Volume 1 of the Historical Works of Gervase of Canterbury. Longman & Company. p. 221.
  5. Hilton, J. L.; Seidelmann, P. K.; Liu, C. (October 1988). "Analysis of ancient Chinese records of occultations between planets and stars" (PDF). Astronomical Journal. 96: 1485. Bibcode:1988AJ.....96.1482H. doi:10.1086/114900. Archived (PDF) from the original on July 28, 2018.