Eclipse

An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either 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.[1] Apart from syzygy, the term eclipse is also used when a spacecraft reaches a position where it can observe two celestial bodies so aligned. An eclipse is the result of either an occultation (completely hidden) or a transit (partially hidden).

The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A binary star system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

For the special cases of solar and lunar eclipses, these only happen during an "eclipse season", the two times of each year when the plane of the Earth's orbit around the Sun crosses with the plane of the Moon's orbit around the Earth. The type of solar eclipse that happens during each season (whether total, annular, hybrid, or partial) depends on apparent sizes of the Sun and Moon. If the orbit of the Earth around the Sun, and the Moon's orbit around the Earth were both in the same plane with each other, then eclipses would happen each and every month. There would be a lunar eclipse at every full moon, and a solar eclipse at every new moon. And if both orbits were perfectly circular, then each solar eclipse would be the same type every month. It is because of the non-planar and non-circular differences that eclipses are not a common event. Lunar eclipses can be viewed from the entire nightside half of the Earth. But solar eclipses, particularly total eclipses occurring at any one particular point on the Earth's surface, are very rare events that can be many decades apart.

Solar eclipse 1999 4 NR
Totality during the 1999 solar eclipse. Solar prominences can be seen along the limb (in red) as well as extensive coronal filaments.

Etymology

The term is derived from the ancient Greek noun ἔκλειψις (ékleipsis), which means "the abandonment", "the downfall", or "the darkening of a heavenly body", which is derived from the verb ἐκλείπω (ekleípō) which means "to abandon", "to darken", or "to cease to exist,"[2] a combination of prefix ἐκ- (ek-), from preposition ἐκ (ek), "out," and of verb λείπω (leípō), "to be absent".[3][4]

Umbra, penumbra and antumbra

Umbra01
Umbra, penumbra and antumbra cast by an opaque object occulting a larger light source

For any two objects in space, a line can be extended from the first through the second. The latter object will block some amount of light being emitted by the former, creating a region of shadow around the axis of the line. Typically these objects are moving with respect to each other and their surroundings, so the resulting shadow will sweep through a region of space, only passing through any particular location in the region for a fixed interval of time. As viewed from such a location, this shadowing event is known as an eclipse.[5]

Typically the cross-section of the objects involved in an astronomical eclipse are roughly disk shaped.[5] The region of an object's shadow during an eclipse is divided into three parts:[6]

  • The umbra, within which the object completely covers the light source. For the Sun, this light source is the photosphere.
  • The antumbra, extending beyond the tip of the umbra, within which the object is completely in front of the light source but too small to completely cover it.
  • The penumbra, within which the object is only partially in front of the light source.
Solar eclipse types
Sun-Moon configurations that produce a total (A), annular (B), and partial (C) solar eclipse

A total eclipse occurs when the observer is within the umbra, an annular eclipse when the observer is within the antumbra, and a partial eclipse when the observer is within the penumbra. During a lunar eclipse only the umbra and penumbra are applicable. This is because Earth's apparent diameter from the viewpoint of the Moon is nearly four times that of the Sun. The same terms may be used analogously in describing other eclipses, e.g., the antumbra of Deimos crossing Mars, or Phobos entering Mars's penumbra.

The first contact occurs when the eclipsing object's disc first starts to impinge on the light source; second contact is when the disc moves completely within the light source; third contact when it starts to move out of the light; and fourth or last contact when it finally leaves the light source's disc entirely.

For spherical bodies, when the occulting object is smaller than the star, the length (L) of the umbra's cone-shaped shadow is given by:

where Rs is the radius of the star, Ro is the occulting object's radius, and r is the distance from the star to the occulting object. For Earth, on average L is equal to 1.384×106 km, which is much larger than the Moon's semimajor axis of 3.844×105 km. Hence the umbral cone of the Earth can completely envelop the Moon during a lunar eclipse.[7] If the occulting object has an atmosphere, however, some of the luminosity of the star can be refracted into the volume of the umbra. This occurs, for example, during an eclipse of the Moon by the Earth—producing a faint, ruddy illumination of the Moon even at totality.

On Earth, the shadow cast during an eclipse moves very approximately at 1 km per sec. This depends on the location of the shadow on the Earth and the angle in which it is moving.[8]

Eclipse cycles

An eclipse cycle takes place when eclipses in a series are separated by a certain interval of time. This happens when the orbital motions of the bodies form repeating harmonic patterns. A particular instance is the saros, which results in a repetition of a solar or lunar eclipse every 6,585.3 days, or a little over 18 years. Because this is not a whole number of days, successive eclipses will be visible from different parts of the world.[9]

Earth–Moon system

Lunar eclipse diagram-en
A symbolic orbital diagram from the view of the Earth at the center, with the Sun and Moon projected upon the celestial sphere, showing the Moon's two nodes where eclipses can occur.

An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth and nodes are aligned twice a year (during an eclipse season), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as a saros.

Between 1901 and 2100 there are the maximum of seven eclipses in:[10]

  • four (penumbral) lunar and three solar eclipses: 1908, 2038.
  • four solar and three lunar eclipses: 1918, 1973, 2094.
  • five solar and two lunar eclipses: 1934.

Excluding penumbral lunar eclipses, there are a maximum of seven eclipses in:[11]

  • 1591, 1656, 1787, 1805, 1918, 1935, 1982, and 2094.

Solar eclipse

2008-08-01 Solar eclipse progression with timestamps
The progression of a solar eclipse on August 1, 2008, viewed from Novosibirsk, Russia. The time between shots is three minutes.

As observed from the Earth, a solar eclipse occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.[12]

Solar eclipse visualisation
Each icon shows the view from the centre of its black spot, representing the Moon (not to scale)

The eclipse magnitude is the fraction of the Sun's diameter that is covered by the Moon. For a total eclipse, this value is always greater than or equal to one. In both annular and total eclipses, the eclipse magnitude is the ratio of the angular sizes of the Moon to the Sun.[13]

Solar eclipses are relatively brief events that can only be viewed in totality along a relatively narrow track. Under the most favorable circumstances, a total solar eclipse can last for 7 minutes, 31 seconds, and can be viewed along a track that is up to 250 km wide. However, the region where a partial eclipse can be observed is much larger. The Moon's umbra will advance eastward at a rate of 1,700 km/h, until it no longer intersects the Earth's surface.

Geometry of a Total Solar Eclipse
Geometry of a total solar eclipse (not to scale)

During a solar eclipse, the Moon can sometimes perfectly cover the Sun because its apparent size is nearly the same as the Sun's when viewed from the Earth. A total solar eclipse is in fact an occultation while an annular solar eclipse is a transit.

When observed at points in space other than from the Earth's surface, the Sun can be eclipsed by bodies other than the Moon. Two examples include when the crew of Apollo 12 observed the Earth to eclipse the Sun in 1969 and when the Cassini probe observed Saturn to eclipse the Sun in 2006.

Lunar eclipse

Eclipse lune
The progression of a lunar eclipse from right to left. Totality is shown with the first two images. These required a longer exposure time to make the details visible.

Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a full moon, when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.[14]

There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue,[15] thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded.[16]

Historical record

Records of solar eclipses have been kept since ancient times. Eclipse dates can be used for chronological dating of historical records. A Syrian clay tablet, in the Ugaritic language, records a solar eclipse which occurred on March 5, 1223 B.C.,[17] while Paul Griffin argues that a stone in Ireland records an eclipse on November 30, 3340 B.C.[18] Positing classical-era astronomers' use of Babylonian eclipse records mostly from the 13th century BC provides a feasible and mathematically consistent[19] explanation for the Greek finding all three lunar mean motions (synodic, anomalistic, draconitic) to a precision of about one part in a million or better. Chinese historical records of solar eclipses date back over 4,000 years and have been used to measure changes in the Earth's rate of spin.[20]

By the 1600s, European astronomers were publishing books with diagrams explaining how lunar and solar eclipses occurred.[21][22] In order to disseminate this information to a broader audience and decrease fear of the consequences of eclipses, booksellers printed broadsides explaining the event either using the science or via astrology.[23]

Other planets and dwarf planets

Gas giants

JupiterandIo
A picture of Jupiter and its moon Io taken by Hubble. The black spot is Io's shadow.
Saturn eclipse
Saturn occults the Sun as seen from the Cassini–Huygens space probe

The gas giant planets (Jupiter,[24] Saturn,[25] Uranus,[26] and Neptune)[27] have many moons and thus frequently display eclipses. The most striking involve Jupiter, which has four large moons and a low axial tilt, making eclipses more frequent as these bodies pass through the shadow of the larger planet. Transits occur with equal frequency. It is common to see the larger moons casting circular shadows upon Jupiter's cloudtops.

The eclipses of the Galilean moons by Jupiter became accurately predictable once their orbital elements were known. During the 1670s, it was discovered that these events were occurring about 17 minutes later than expected when Jupiter was on the far side of the Sun. Ole Rømer deduced that the delay was caused by the time needed for light to travel from Jupiter to the Earth. This was used to produce the first estimate of the speed of light.[28]

On the other three gas giants, eclipses only occur at certain periods during the planet's orbit, due to their higher inclination between the orbits of the moon and the orbital plane of the planet. The moon Titan, for example, has an orbital plane tilted about 1.6° to Saturn's equatorial plane. But Saturn has an axial tilt of nearly 27°. The orbital plane of Titan only crosses the line of sight to the Sun at two points along Saturn's orbit. As the orbital period of Saturn is 29.7 years, an eclipse is only possible about every 15 years.

The timing of the Jovian satellite eclipses was also used to calculate an observer's longitude upon the Earth. By knowing the expected time when an eclipse would be observed at a standard longitude (such as Greenwich), the time difference could be computed by accurately observing the local time of the eclipse. The time difference gives the longitude of the observer because every hour of difference corresponded to 15° around the Earth's equator. This technique was used, for example, by Giovanni D. Cassini in 1679 to re-map France.[29]

Mars

PIA05553
Transit of Phobos from Mars, as seen by the Mars Opportunity rover (10 March 2004).

On Mars, only partial solar eclipses (transits) are possible, because neither of its moons is large enough, at their respective orbital radii, to cover the Sun's disc as seen from the surface of the planet. Eclipses of the moons by Mars are not only possible, but commonplace, with hundreds occurring each Earth year. There are also rare occasions when Deimos is eclipsed by Phobos.[30] Martian eclipses have been photographed from both the surface of Mars and from orbit.

Pluto

Pluto, with its proportionately largest moon Charon, is also the site of many eclipses. A series of such mutual eclipses occurred between 1985 and 1990.[31] These daily events led to the first accurate measurements of the physical parameters of both objects.[32]

Mercury and Venus

Eclipses are impossible on Mercury and Venus, which have no moons. However, both have been observed to transit across the face of the Sun. There are on average 13 transits of Mercury each century. Transits of Venus occur in pairs separated by an interval of eight years, but each pair of events happen less than once a century.[33] According to NASA, the next pair of transits will occur on December 10, 2117 and December 8, 2125. Transits on Mercury are much more common.[34]

Eclipsing binaries

A binary star system consists of two stars that orbit around their common centre of mass. The movements of both stars lie on a common orbital plane in space. When this plane is very closely aligned with the location of an observer, the stars can be seen to pass in front of each other. The result is a type of extrinsic variable star system called an eclipsing binary.

The maximum luminosity of an eclipsing binary system is equal to the sum of the luminosity contributions from the individual stars. When one star passes in front of the other, the luminosity of the system is seen to decrease. The luminosity returns to normal once the two stars are no longer in alignment.[35]

The first eclipsing binary star system to be discovered was Algol, a star system in the constellation Perseus. Normally this star system has a visual magnitude of 2.1. However, every 2.867 days the magnitude decreases to 3.4 for more than nine hours. This is caused by the passage of the dimmer member of the pair in front of the brighter star.[36] The concept that an eclipsing body caused these luminosity variations was introduced by John Goodricke in 1783.[37]

See also

Types

Sun - Moon - Earth: Solar eclipse | annular eclipse | hybrid eclipse | partial eclipse

Sun - Earth - Moon: Lunar eclipse | penumbral eclipse | partial lunar eclipse | central lunar eclipse

Sun - Phobos - Mars: Transit of Phobos from Mars | Solar eclipses on Mars

Sun - Deimos - Mars: Transit of Deimos from Mars | Solar eclipses on Mars

Other types: Solar eclipses on Jupiter | Solar eclipses on Saturn | Solar eclipses on Uranus | Solar eclipses on Neptune | Solar eclipses on Pluto

References

  1. ^ Staff (March 31, 1981). "Science Watch: A Really Big Syzygy" (Press release). The New York Times. Archived from the original on December 10, 2008. Retrieved 2008-02-29.
  2. ^ "Https://www.in.gr/dictionary/lookup.asp/?Word=%E5%EA%EB%E5%DF%F0%F9+++&x=0&y=0". Retrieved 2009-09-24. External link in |title= (help)
  3. ^ "Free online English Greek dictionary. LingvoSoft free online English dictionary". lingvozone.com. Archived from the original on 2013-01-28.
  4. ^ "Google Translate". translate.google.com.
  5. ^ a b Westfall, John; Sheehan, William (2014), Celestial Shadows: Eclipses, Transits, and Occultations, Astrophysics and Space Science Library, 410, Springer, pp. 1−5, ISBN 978-1493915354.
  6. ^ Espenak, Fred (September 21, 2007). "Glossary of Solar Eclipse Terms". NASA. Archived from the original on February 24, 2008. Retrieved 2008-02-28.
  7. ^ Green, Robin M. (1985). Spherical Astronomy. Oxford University Press. ISBN 978-0-521-31779-5.
  8. ^ "Speed of eclipse shadow? - Sciforums". sciforums.com. Archived from the original on 2015-04-02.
  9. ^ Espenak, Fred (July 12, 2007). "Eclipses and the Saros". NASA. Archived from the original on 2007-10-30. Retrieved 2007-12-13.
  10. ^ "Eclipse Statistics". moonblink.info. Archived from the original on 2014-05-27.
  11. ^ Gent, R.H. van. "A Catalogue of Eclipse Cycles". staff.science.uu.nl. Archived from the original on 2011-09-05.
  12. ^ Hipschman, R. (2015-10-29). "Solar Eclipse: Why Eclipses Happen". Archived from the original on 2008-12-05. Retrieved 2008-12-01.
  13. ^ Zombeck, Martin V. (2006). Handbook of Space Astronomy and Astrophysics (Third ed.). Cambridge University Press. p. 48. ISBN 978-0-521-78242-5.
  14. ^ Staff (January 6, 2006). "Solar and Lunar Eclipses". NOAA. Archived from the original on May 12, 2007. Retrieved 2007-05-02.
  15. ^ Phillips, Tony (February 13, 2008). "Total Lunar Eclipse". NASA. Archived from the original on March 1, 2008. Retrieved 2008-03-03.
  16. ^ Ancient Timekeepers, "Archived copy". 2011-09-16. Archived from the original on 2011-10-26. Retrieved 2011-10-25.CS1 maint: Archived copy as title (link)
  17. ^ de Jong, T.; van Soldt, W. H. (1989). "The earliest known solar eclipse record redated". Nature. 338 (6212): 238–240. Bibcode:1989Natur.338..238D. doi:10.1038/338238a0. Archived from the original on 2007-10-15. Retrieved 2007-05-02.
  18. ^ Griffin, Paul (2002). "Confirmation of World's Oldest Solar Eclipse Recorded in Stone". The Digital Universe. Archived from the original on 2007-04-09. Retrieved 2007-05-02.
  19. ^ See DIO 16 Archived 2011-07-26 at the Wayback Machine p.2 (2009). Though those Greek and perhaps Babylonian astronomers who determined the three previously unsolved lunar motions were spread over more than four centuries (263 BC to 160 AD), the math-indicated early eclipse records are all from a much smaller span Archived 2015-04-02 at the Wayback Machine: the 13th century BC. The anciently attested Greek technique: use of eclipse cycles, automatically providing integral ratios, which is how all ancient astronomers' lunar motions were expressed. Long-eclipse-cycle-based reconstructions precisely produce all of the 24 digits appearing in the three attested ancient motions just cited: 6247 synod = 6695 anom (System A), 5458 synod = 5923 drac (Hipparchos), 3277 synod = 3512 anom (Planetary Hypotheses). By contrast, the System B motion, 251 synod = 269 anom (Aristarchos?), could have been determined without recourse to remote eclipse data, simply by using a few eclipse-pairs 4267 months apart.
  20. ^ "Solar Eclipses in History and Mythology". Bibliotheca Alexandrina. Archived from the original on 2007-04-08. Retrieved 2007-05-02.
  21. ^ Girault, Simon (1592). Globe dv monde contenant un bref traite du ciel & de la terra. Langres, France. p. Fol. 8V.
  22. ^ Hevelius, Johannes (1652). Observatio Eclipseos Solaris Gedani. Danzig, Poland.
  23. ^ Stephanson, Bruce; Bolt, Marvin; Friedman, Anna Felicity (2000). The Universe Unveiled: Instruments and Images through History. Cambridge, UK: Cambridge University Press. pp. 32–33. ISBN 978-0521791434.
  24. ^ "Start eclipse of the Sun by Callisto from the center of Jupiter" (Observed at 00:28 UT). JPL Solar System Simulator. 3 June 2009. Retrieved 2008-06-05. External link in |publisher= (help)
  25. ^ "Eclipse of the Sun by Titan from the center of Saturn" (Observed at 02:46 UT). JPL Solar System Simulator. 3 August 2009. Retrieved 2008-06-05. External link in |publisher= (help)
  26. ^ "Brief Eclipse of the Sun by Miranda from the center of Uranus" (Observed at 19:58 UT (JPL Horizons S-O-T=0.0565)). JPL Solar System Simulator. 22 January 2007. Retrieved 2008-06-05. External link in |publisher= (help)
  27. ^ "Transit of the Sun by Nereid from the center of Neptune" (Observed at 20:19 UT (JPL Horizons S-O-T=0.0079)). JPL Solar System Simulator. 28 March 2006. Retrieved 2008-06-05. External link in |publisher= (help)
  28. ^ "Roemer's Hypothesis". MathPages. Archived from the original on 2011-02-24. Retrieved 2007-01-12.
  29. ^ Cassini, Giovanni D. (1694). "Monsieur Cassini His New and Exact Tables for the Eclipses of the First Satellite of Jupiter, Reduced to the Julian Stile, and Meridian of London". Philosophical Transactions of the Royal Society. 18 (207–214): 237–256. doi:10.1098/rstl.1694.0048. JSTOR 102468. Archived from the original on 2013-09-08. Retrieved 2007-04-30.
  30. ^ Davidson, Norman (1985). Astronomy and the Imagination: A New Approach to Man's Experience of the Stars. Routledge. ISBN 978-0-7102-0371-7.
  31. ^ Buie, M. W.; Polk, K. S. (1988). "Polarization of the Pluto-Charon System During a Satellite Eclipse". Bulletin of the American Astronomical Society. 20: 806. Bibcode:1988BAAS...20..806B.
  32. ^ Tholen, D. J.; Buie, M. W.; Binzel, R. P.; Frueh, M. L. (1987). "Improved Orbital and Physical Parameters for the Pluto-Charon System". Science. 237 (4814): 512–514. Bibcode:1987Sci...237..512T. doi:10.1126/science.237.4814.512. PMID 17730324. Archived from the original on 2008-07-06. Retrieved 2008-03-11.
  33. ^ Espenak, Fred (May 29, 2007). "Planetary Transits Across the Sun". NASA. Archived from the original on March 11, 2008. Retrieved 2008-03-11.
  34. ^ "When will the next transits of Mercury and Venus occur during a total solar eclipse? | Total Solar Eclipse 2017". eclipse2017.nasa.gov. Archived from the original on 2017-09-18. Retrieved 2017-09-25.
  35. ^ Bruton, Dan. "Eclipsing binary stars". Midnightkite Solutions. Archived from the original on 2007-04-14. Retrieved 2007-05-01.
  36. ^ Price, Aaron (January 1999). "Variable Star Of The Month: Beta Persei (Algol)". AAVSO. Archived from the original on 2007-04-05. Retrieved 2007-05-01.
  37. ^ Goodricke, John; Englefield, H. C. (1785). "Observations of a New Variable Star". Philosophical Transactions of the Royal Society of London. 75: 153–164. Bibcode:1785RSPT...75..153G. doi:10.1098/rstl.1785.0009.

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22nd century

The 22nd (twenty-second) century will be a century of the Anno Domini or Common Era in accordance with the Gregorian calendar. It will be the century following the current 21st century, beginning on January 1, 2101 and ending on December 31, 2200.

Eclipse (software)

Eclipse is an integrated development environment (IDE) used in computer programming, and is the most widely used Java IDE. It contains a base workspace and an extensible plug-in system for customizing the environment. Eclipse is written mostly in Java and its primary use is for developing Java applications, but it may also be used to develop applications in other programming languages via plug-ins, including Ada, ABAP, C, C++, C#, Clojure, COBOL, D, Erlang, Fortran, Groovy, Haskell, JavaScript, Julia, Lasso, Lua, NATURAL, Perl, PHP, Prolog, Python, R, Ruby (including Ruby on Rails framework), Rust, Scala, and Scheme. It can also be used to develop documents with LaTeX (via a TeXlipse plug-in) and packages for the software Mathematica. Development environments include the Eclipse Java development tools (JDT) for Java and Scala, Eclipse CDT for C/C++, and Eclipse PDT for PHP, among others.

The initial codebase originated from IBM VisualAge. The Eclipse software development kit (SDK), which includes the Java development tools, is meant for Java developers. Users can extend its abilities by installing plug-ins written for the Eclipse Platform, such as development toolkits for other programming languages, and can write and contribute their own plug-in modules. Since the introduction of the OSGi implementation (Equinox) in version 3 of Eclipse, plug-ins can be plugged-stopped dynamically and are termed (OSGI) bundlesEclipse software development kit (SDK) is free and open-source software, released under the terms of the Eclipse Public License, although it is incompatible with the GNU General Public License. It was one of the first IDEs to run under GNU Classpath and it runs without problems under IcedTea.

Eclipse cycle

Eclipses may occur repeatedly, separated by certain intervals of time: these intervals are called eclipse cycles. The series of eclipses separated by a repeat of one of these intervals is called an eclipse series.

Gamma (eclipse)

Gamma (denoted as γ) of an eclipse describes how centrally the shadow of the Moon or Earth strikes the other body. This distance, measured at the moment when the axis of the shadow cone passes closest to the center of the Earth or Moon, is stated as a fraction of the equatorial radius of the Earth or Moon.

Lunar eclipse

A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy), with Earth between the other two. A lunar eclipse can occur only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon's proximity to either node of its orbit.

During a total lunar eclipse, Earth completely blocks direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light. Due to this reddish color, a totally eclipsed Moon is sometimes called a blood moon.

Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse lasts a few hours, while a total solar eclipse lasts only a few minutes at any given place, due to the smaller size of the Moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.

For the date of the next eclipse, see the section Recent and forthcoming lunar eclipses.

Magnitude of eclipse

The magnitude of eclipse is the fraction of the angular diameter of a celestial body being eclipsed. This applies to all celestial eclipses. The magnitude of a partial or annular solar eclipse is always between 0.0 and 1.0, while the magnitude of a total solar eclipse is always greater than or equal to 1.0.

This measure should not be confused with the covered fraction of the apparent area (disk) of the eclipsed body, whereas the magnitude of an eclipse is strictly a ratio of diameters. Neither should it be confused with the astronomical magnitude scale of apparent brightness.

Mitsubishi Eclipse

The Mitsubishi Eclipse is a sport compact car that was produced by Mitsubishi in four generations between 1989 and 2011. A convertible body style was added during the 1996 model year.

The first two generations (1G and 2G) share the automobile platform and parts with the rebadged Eagle Talon and Plymouth Laser captive imports. They were built during Mitsubishi Motors' close relationship with Chrysler Corporation. Their partnership was known as Diamond-Star Motors (DSM). In Japan, the first two generations were sold at a specific Japanese retail chain called Mitsubishi Car Plaza. The third generation (3G) shared a redesigned platform with the Chrysler Sebring and Dodge Stratus. During May 2005, the fourth, and final, generation (4G) Eclipse was introduced, replacing the Chrysler platform used in the first three generations with the PS platform.According to Mitsubishi Motors, the Eclipse was named after an unbeaten 18th-century English racehorse that had won 26 races.The Eclipse was officially marketed in North America, Oman, South Korea, the Philippines, Brazil, Saudi Arabia, Kuwait, UAE, and China. At the end of August 2011, the final Eclipse rolled off the assembly line, and was auctioned off, the proceeds donated to charity.In January 2017, Mitsubishi stated that it plans to resurrect the Eclipse name on a compact crossover vehicle, titled the Eclipse Cross, which debuted at the 2017 Geneva Auto Show in March. The new Eclipse will slot between the Mitsubishi ASX and Mitsubishi Outlander in the Mitsubishi lineup.

Saros (astronomy)

The saros ( (listen)) is a period of approximately 223 synodic months (approximately 6585.3211 days, or 18 years, 11 days, 8 hours), that can be used to predict eclipses of the Sun and Moon. One saros period after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, a near straight line, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle. A sar is one half of a saros.A series of eclipses that are separated by one saros is called a saros series.

Solar eclipse

A solar eclipse occurs when an observer (on Earth) passes through the shadow cast by the Moon which fully or partially blocks ("occults") the Sun. This can only happen when the Sun, Moon and Earth are nearly aligned on a straight line in three dimensions (syzygy) during a new moon when the Moon is close to the ecliptic plane. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.

If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every new moon. However, since the Moon's orbit is tilted at more than 5 degrees to the Earth's orbit around the Sun, its shadow usually misses Earth. A solar eclipse can only occur when the moon is close enough to the ecliptic plane during a new moon. Special conditions must occur for the two events to coincide because the Moon's orbit crosses the ecliptic at its orbital nodes twice every draconic month (27.212220 days) while a new moon occurs one every synodic month (29.530587981 days). Solar (and lunar) eclipses therefore happen only during eclipse seasons resulting in at least two, and up to five, solar eclipses each year; no more than two of which can be total eclipses.Total eclipses are rare because the timing of the new moon within the eclipse season needs to be more exact for an alignment between the observer (on Earth) and the centers of the Sun and Moon. In addition, the elliptical orbit of the Moon often takes it far enough away from Earth that its apparent size is not large enough to block the Sun entirely. Total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's full shadow or umbra.

An eclipse is a natural phenomenon. However, in some ancient and modern cultures, solar eclipses were attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.

Since looking directly at the Sun can lead to permanent eye damage or blindness, special eye protection or indirect viewing techniques are used when viewing a solar eclipse. It is technically safe to view only the total phase of a total solar eclipse with the unaided eye and without protection; however, this is a dangerous practice, as most people are not trained to recognize the phases of an eclipse, which can span over two hours while the total phase can only last a maximum of 7.5 minutes for any one location. People referred to as eclipse chasers or umbraphiles will travel to remote locations to observe or witness predicted central solar eclipses.

Solar eclipse of April 8, 2024

A total solar eclipse will take place on Monday, April 8, 2024, visible across North America. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

With a magnitude of 1.0566, its longest duration of totality will be of four minutes and 28 seconds near the town of Nazas, Durango, Mexico, and the nearby city of Torreón, Coahuila.

This eclipse will be the first total solar eclipse to be visible from Canada since February 26, 1979, the first in Mexico since July 11, 1991, and the first in the U.S. since August 21, 2017.

It will be the only total solar eclipse in the 21st century where totality is visible in Mexico, the United States of America, and Canada.

Solar eclipse of August 11, 1999

A total solar eclipse occurred on 11 August 1999 with an eclipse magnitude of 1.029. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

The path of the Moon's shadow began in the Atlantic Ocean and, before noon, was traversing the southern United Kingdom, northern France, Belgium, Luxembourg, southern Germany, Austria, Slovenia, Croatia, Hungary, and northern FR Yugoslavia (Vojvodina). The eclipse's maximum was at 11:03 UTC at 45.1°N 24.3°E / 45.1; 24.3 in Romania (next to a town called Ocnele Mari near Râmnicu Vâlcea); and it continued across Bulgaria, the Black Sea, Turkey, northeastern tip of Syria, northern Iraq, Iran, southern Pakistan and Srikakulam in India and ended in the Bay of Bengal.

It was the first total eclipse visible from Europe since 22 July 1990, and the first visible in the United Kingdom since 29 June 1927.

Solar eclipse of August 21, 2017

The solar eclipse of August 21, 2017, dubbed the "Great American Eclipse" by the media, was a total solar eclipse visible within a band that spanned the entire contiguous United States, passing from the Pacific to the Atlantic coasts. As a partial solar eclipse, it was visible on land from Nunavut in northern Canada to as far south as northern South America. In northwestern Europe and Africa, it was partially visible in the late evening. In Asia, it was visible only at the eastern extremity, the Chukchi Peninsula.

Prior to this event, no solar eclipse had been visible across the entire contiguous United States since June 8, 1918; not since the February 1979 eclipse had a total eclipse been visible from anywhere in the mainland United States. The path of totality touched 14 states, and the rest of the U.S. had a partial eclipse. The area of the path of totality was about 16 percent of the area of the United States, with most of this area over the ocean, not land. The event's shadow began to cover land on the Oregon coast as a partial eclipse at 4:05 p.m. UTC (9:05 a.m. PDT), with the total eclipse beginning there at 5:16 p.m. UTC (10:16 a.m. PDT); the total eclipse's land coverage ended along the South Carolina coast at about 6:44 p.m. UTC (2:44 p.m. EDT). Visibility as a partial eclipse in Honolulu, Hawaii began with sunrise at 4:20 p.m. UTC (6:20 a.m. HST) and ended by 5:25 p.m. UTC (7:25 a.m. HST).This total solar eclipse marked the first such event in the smartphone and social media era in America. Information, personal communication, and photography were widely available as never before, capturing popular attention and enhancing the social experience.

Marriage proposals took place coinciding with the eclipse, and at least one wedding was also planned and took place to coincide with the eclipse. Logistical problems were expected with the influx of visitors, especially for smaller communities. The sale of counterfeit eclipse glasses was also anticipated to be a hazard for eye injuries.Future total solar eclipses will cross the United States in April 2024 (12 states) and August 2045 (10 states), and annular solar eclipses—wherein the Moon appears smaller than the Sun—will occur in October 2023 (9 states) and June 2048 (9 states).

Solar eclipse of July 2, 2019

A total solar eclipse will occur on July 2, 2019 with a magnitude of 1.0459. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

Totality will be visible from the southern Pacific Ocean east of New Zealand to the Coquimbo Region in Chile and Argentina at sunset, with the maximum of 4 minutes 32 seconds visible from the Pacific Ocean. Astronomers Without Borders collected eclipse glasses for redistribution to Latin America and Asia for their 2019 eclipses from the solar eclipse of August 21, 2017. A total solar eclipse will cross this region on December 14, 2020 just 531 days later.

Solar eclipse of July 22, 2009

A total solar eclipse occurred on July 22, 2009. It was the longest total solar eclipse during the 21st century. It lasted a maximum of 6 minutes and 39 seconds off the coast of Southeast Asia, causing tourist interest in eastern China, Pakistan, Japan, India, Nepal and Bangladesh.

Solar eclipse of March 29, 2006

A total solar eclipse occurred on March 28–29, 2006. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. It was visible from a narrow corridor which traversed half the Earth. The magnitude, that is, the ratio between the apparent sizes of the Moon and that of the Sun, was 1.052, and it was part of Saros 139.

Star Destroyer

Star Destroyers are capital ships in the fictional Star Wars universe. The Imperial Star Destroyer, which first appears in the first seconds of Star Wars (1977), is "the signature vessel of the Imperial fleet". Each star destroyer functioned as a forward operating base responsible for safeguarding multiple planets, trade routes and systems, and carried enough firepower to subdue an entire planetary system or annihilate a small rebel fleet. The term "Star Destroyer" also refers to other "triangular" vessels in the franchise; the successful v-shaped designs are explained in Legends as originating from Sith influence, and have been adapted by numerous factions for a wide variety of applications.

Numerous Star Destroyer models and toys have been released, and the iconic scene featuring the vessel's first appearance pursuing Princess Leia's starship has been called a milestone in special effects history.

The Twilight Saga (film series)

The Twilight Saga is a series of five romance fantasy films from Summit Entertainment based on the four novels by American author Stephenie Meyer. The films star Kristen Stewart, Robert Pattinson, and Taylor Lautner. The series has grossed over $3.3 billion in worldwide receipts. The first installment, Twilight, was released on November 21, 2008. The second installment, New Moon, followed on November 20, 2009, breaking box office records as the biggest midnight screening and opening day in history, grossing an estimated $72.7 million. The third installment, Eclipse, was released on June 30, 2010, and was the first Twilight film to be released in IMAX.The series was in development since 2004 at Paramount Pictures, during which time a screen adaptation of Twilight that differed significantly from the novel was written. Three years later, Summit Entertainment acquired the rights to the film. After Twilight grossed $35.7 million on its opening day, Summit Entertainment announced they would begin production on New Moon; they had acquired the rights to the remaining novels earlier that same month. A two-part adaptation of Breaking Dawn began shooting in November 2010 with release dates of November 18, 2011, and November 16, 2012, respectively.

Total Eclipse of the Heart

"Total Eclipse of the Heart" is a song recorded by Welsh singer Bonnie Tyler. It was written and produced by Jim Steinman, and released on Tyler's fifth studio album, Faster Than the Speed of Night (1983). The song was released as a single by Columbia Records on 11 February 1983 in the United Kingdom and on 31 May 1983 in the United States.

The song became Tyler's biggest career hit, topping the UK Singles Chart, and becoming the fifth-best-selling single in 1983 in the United Kingdom. In the United States, the single spent four weeks at the top of the charts, and was Billboard's number-six song of the year for 1983.

Worldwide, the single has sales in excess of 6 million copies and was certified Gold by the Recording Industry Association of America (RIAA) for sales of over 1 million copies after its release, updated to Platinum in 2001 when the certification threshold changed. In 2015, the song was voted by the British public as the nation's third favourite 1980s number one in a poll for ITV.

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