What is Eclipse: Definition and 117 Discussions

An eclipse is an astronomical event that 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. 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 when that line of intersecting planes points near the Sun. 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.

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  1. S

    I Exploring Saros Cycles & Eclipse Differences

    Is the difference in the eclipses of a Saros cycle (i.e., other than the longitude) due to the fact that a Saros cycle is exactly 223 synodic months but 241.999 draconic months and 238.992 anomalistic months, with the 0.001 & 0.008 month differences causing the slight differences in the eclipses...
  2. S

    B Has there ever been a planet-planet eclipse (i.e., observed from Earth)?

    The upcoming conjunction of Jupiter & Saturn has got me thinking. I wonder if it has ever been observed (and hopefully photographed) of one planet's disc even partially taking over another's. I have seen a photo of Saturn doing this with the Moon, but I don't think I've ever seen one of a pair...
  3. S

    B If a coronal ejection like this happened during a total eclipse ....

    would spectators be able to see it? How about with 12X binoculars? https://www.nytimes.com/2020/09/15/science/sun-solar-cycle.html
  4. mahonskey

    I Hypothetical Eclipse Calculation

    Hypothetical: Approximately how far from Earth would a star the size of the sun have to be for an object the size of a quantum particle to cause a total eclipse of that star when orbiting the Earth at a distance equal to that of Earth to the center fro the moon?
  5. mahonskey

    B Quantum total eclipse of the sun?

    This might be total nonsense, but the thought popped into my head while I was trying to get to sleep, so I thought I see if I could find any advanced help with the following hypothetical: If light were instantaneous, how far from Earth would the sun have to be to cause a quark orbiting in place...
  6. S

    I What stars were observed @ 1919 solar eclipse to prove relativity?

    Was there a published report of exactly which stars which were supposed to be at position A but were observed at position B, etc.?
  7. Q

    B Is sunlight through gaps in leaves during an eclipse decohered?

    Is the reason you can make out the shape of the sun and the moon is because the gaps between the leaves cause the light to be photons instead of waves?
  8. Wrichik Basu

    How to prepare my camera for a solar eclipse

    There will be a solar eclipse on 26th December that can be viewed from my city. In addition to buying safety glasses, I also want to prepare my camera, if possible. The camera is a Panasonic FZ-70. I have a UV protector and four ND filters - 2, 4, 8, 16. I am also buying a circular polarizer...
  9. G

    A Measuring Deflection of Star Light During Eclipse: Separating Space-Time Effects

    There is the famous experiment of measuring the "movement" of a star close to the sun during an eclipse. The stars position is determined before the disc of the sun moves just under it and than the position is again measured when the sun moves just "under" the star. The star will have appeared...
  10. S

    Requirements for seeing a Total Solar Eclipse?

    From my understanding, for an observer to see a total solar eclipse, 1) the Moon's orbit has to be near aligned with the Earth's Orbit, 2)such that the New moon's Umbra falls on Earth, and 3) the observer must be within this cast umbra. But for a partial solar eclipse, since the Penumbra of the...
  11. S

    B How common for almost same solar eclipse 17 months later?

    I see that South America (Chile/Argentina) will be getting a total solar eclipse this winter (i.e., winter there) and then another one only 17 months later that seems to be along the same type of path, albeit a little bit south. This can't be very common...
  12. OmCheeto

    Stargazing Stellar Eclipse on Feb 18/19, 2019

    Sirius, the brightest star in the sky, might be eclipsed by an asteroid in a few days: https://www.skyandtelescope.com/observing/will-sirius-disappear/ Can a 7-kilometer-wide asteroid make Sirius disappear? You bet it can. That just might happen on Monday night, February 18th. That evening...
  13. S

    B Why didn't the Moon go fully red for this eclipse?

    (For reference, I am around coordinates ( +30 , -90 ), and this is the January 2019 lunar eclipse.) I am typing this at supposedly mid-eclipse, and yet I see a thin crescent of white (ash?) along one side. It seems that the Moon should be well within the umbra at this point.
  14. russ_watters

    Stargazing Lunar Eclipse Jan 20-21, 2019

    Anyone else watching the lunar eclipse tonight? It starts at about 9:30PM EST, with totality at 11:41. It's cold and windy in PA, but at least it's mostly clear. Here's a couple of pre-eclipse photos:
  15. A

    B Solar Eclipse by a Black Hole

    Dear All Concerns Black Hole is formed at the end of life of a big star. The mass of such star should be equal to 5-10 solar masses. But I am imaging very small moving black hole coming to our solar system and passing between our Earth planet and the sun thereby creating solar eclipse of unique...
  16. S

    B Does a partial solar eclipse never completely rise?

    It seems that a partial solar eclipse is one in which the eclipse circle never completely rises, and it essentially is only a sunrise or sunset eclipse, with the point at which it goes from sunrise to sunset being that location in the polar region where the eclipse is at "high noon" but which it...
  17. J

    Can total lunar eclipse and partial lunar eclipse happen at the same time?

    Can total lunar eclipse and partial lunar eclipse be happened at the same time? So, do we call it partial lunar eclipse when the total lunar eclipse happen just before?
  18. Space_Girl

    Stargazing Solar Eclipse on Feb 15, 2018 | Time and Date

  19. Charles Link

    B Tonight's full moon and lunar eclipse

    Hello, I don't see any other post about tonight's full moon and lunar eclipse, so I thought I would mention it.
  20. smodak

    B Einstein Proven Right by 2017 Eclipse? Investigation

    Did the 2017 eclipse prove Einstein was right or the jury is still out? I can't find any references to the new measurements and what they proved (or did not).
  21. FactChecker

    NASA What do we learn from eclipse that the NASA IRIS doesn't tell us?

    What can we learn from a solar eclipse that the NASA IRIS program doesn't tell us? (and why)
  22. A

    B Questions about the eclipse

    I observed the eclipse from Washington DC area yesterday. I have a few questions. from the eclipse map and youtube clips ppl uploaded, the eclipse starts in Oregon and sweep across states. questions: 1. I know Earth rotate around itself from west towards east every 24 hrs, is this the main...
  23. R

    B Today's Solar eclipse A dud

    Why didn't the Earth get dark? Apparently, even in a total eclipse the moon doesn't block out the total circumference of the sun. Is it a matter of geometry?
  24. T

    I Eclipse Path Explained: Earth's Axis & Moon's Incline

    Hi there, I've watched this video: . I have been curious the whole day why the eclipse path seems to be curved and obviously in our latitude. Is it because of both the moon's orbital plane and the tilt of the Earth's axis? If it went across the US, that is a lot more than 5 degrees (moon...
  25. Xilus

    NASA NASA Eclipse Calculations Accuracy

    How accurate do you think NASA's eclipse calculations are? Will that aircraft provide accurate moon trajectory?
  26. MarkFL

    MHB Solar Eclipse 2017 - Share Your Viewing Plans & Memories

    Hello MHB Community! :D As I'm sure most of you who live in the U.S. are aware, we will be witness to a solar eclipse on the 21st of August and the path of totality will cut across the continental U.S.: I live in NE Florida, and will experience almost 90% obscurity, but I have family in TN...
  27. C

    How long does it take for the temperature on Earth to....

    How long does it take for the temperature on Earth to cool down after the sun has set? I want to know if the total solar eclipse will change the temperature.
  28. Parker Hame

    Will Michigan Ever Get An Eclipse

    I am from Michigan, I read about the August 2017 eclipse and it's not passing through my home state. I was wondering, is there any formula or even just general common sense that will say if their will ever be a Eclipse in Michigan? I don't care if it's a solar OR lunar eclipse. Will there be an...
  29. Blank_Stare

    Stargazing Solar Con? Eclipse road trip to Makanda Illinois

    I think I may be heading to Makanda Illinois, on August 21, for the Eclipse. (Where I live in Michigan, it will only be about 80% - I want the full effect...) In all likelihood, considering my age, and how mobile I may be by the next time there is a full eclipse in the US, I have decided I...
  30. N

    Why the data does not print out with eclipse in unbuntu?

    Dear group, I am using Eclipse in the Ubuntu operation system and trying to print out this data from the begin to the string "END OF HEADER" but I do not understand why it did not give me the one as I expected. I also used this file "albe0320_1.17n" to test and it worked, but the file that I...
  31. parshyaa

    B Understanding the Mystery of Sunlight Bending During a Solar Eclipse

    during solar eclipse , moon's shadow on Earth is almost a point [267 km which is a 0.00000523 % of Earth's surface area] which means that sun light must bend, if it is not bending then we would never get a point shadow of moon on earth. now the question arises why sun light bends, is it a...
  32. Borg

    Stargazing U.S. Solar Eclipse of Aug. 21, 2017

    I've been waiting for this for a long time and it's just a little more than a year away now. This will be the opportunity of a lifetime for people in the U.S. The 2017 solar eclipse will be visible across the width of the entire U.S! The points of Greatest Eclipse and Greatest Duration are...
  33. L

    Fictional eclipse recurrence

    Dear all, I have been reading through this article about how often different types of eclipse (eclipse cycles) can occur. I'm presuming that all fictional eclipses have to be variations of these? Even with a fictional planet/moon/solar system? But what if the desired recurrence of an eclipse...
  34. H

    Lunar super eclipse Sept. 27th. 2015

    Below is the link to the Lunar super eclipse Sept. 27th. It won't happen again until 2033. http://finance.yahoo.com/news/theres-rare-supermoon-total-lunar-205421688.html?amp;soc_trk=ma&soc_src=mail&soc_trk=ma
  35. C

    Lunar and Solar eclipse - same times a year?

    Hi, Just wondering: The lunar orbit around the Earth is tilted 5.1 degree with respect to the Earth's orbit around the sun (as described in the video), so only at 2 times during the year the Earth is aligned with the sun such that lunar eclipses can happen IF the moon is behind the Earth...
  36. Shreyas Shree

    Make an android app in eclipse using python

    How to make an android app using python on eclipse.
  37. M

    Java NullPointerException error in Java (Eclipse)

    class Cellphone { private String brand; private long serialNumber; private double Price; public Cellphone (String br, long sN, double Pr) { brand= br; serialNumber = sN; Price = Pr; } public Cellphone(Cellphone aCellphone)...
  38. T

    Scientific importance of total Solar eclipses?

    I was wondering whether there is an actual scientific point of taking ground-based photographs of the Solar corona during total eclipses on Earth. It seems to attract a lot of attention from well equipped amateurs around the world and the pictures of the fine plasma structure surely look great...
  39. Garth

    Solar Eclipse 20 March 2015

    Just to let everyone know here in the UK we are waiting expectantly for the Solar Eclipse tomorrow morning - max at around 9.30am. 98% coverage in the north of Scotland and the Orkneys, Hebrides and Shetland islands, 85% down here in the south. The totality shadow crosses from the North...
  40. S

    Confusion regarding Solar Eclipse

    If solar eclipse occurs at 12h 12m 12s actually. Then at what time one will see it on earth. Will the speed of light affect the time if moon starts covering sun at 12 h 12 m 12s when one will see covering on earth? at what time? I just want to know I am just curious do you think the time taken...
  41. L

    Smallest angle of inclination between two stars for eclipse

    Homework Statement Assume two stars are in circular orbit around a mutual center of mass and are separated by d = a. Assume angle of inclination is i and stellar radii are r1 and r2. Find an expression for the smallest angle of inclination that will just barely produce an eclipse. Homework...
  42. T

    Exomoon in Permenant Shade?

    Hello, thank you for reading my post. For a story I am working on I am wondering about the plausibility of some star and planet configurations. I have done some web research on my own and learned a lot, but for some things I think my vocabulary and knowledge is too limited to search for exactly...
  43. lpetrich

    I saw the 23 Oct 2014 N America partial solar eclipse

    I saw it yesterday. I live in the Pacific Northwest, which was clouded over. But at about 2:45 - 3:00 PM PDT, at local maximum eclipse, there was a break in the lower clouds, and I could see the Sun through the upper clouds. It was rather fuzzy-looking, but I could see a bite out of it from the...
  44. davenn

    Total Lunar Eclipse 8th Oct 2014

    hi guys and gals a total lunar eclipse will be visible for all Pacific and parts of it for most of USA parts of South America, Central Asia cheers Dave
  45. C

    Found: The First Double Star That BRIGHTENS During Eclipse

    First discovery of double star that brightens during eclipse Einstein's general theory of relativity explains the phenomenon by Dr. Ken Croswell For the first time, astronomers have seen a double star brighten rather than fade when one star passes in front of its companion. Predicted...
  46. C

    Lunar Eclipse: Umbra and penumbra radii

    Homework Statement Find the radii of the umbra and penumbra circles drawn drawn perpendicular to the EMS axis, formed at a distance equal to that of the moon from the Earth. Homework Equations (From: http://www.opticiansfriend.com/articles/equations.html#Shadows) D2 / L1 = (P + U) /...
  47. Evo

    Blood moon Total Eclipse tonight

  48. N

    Solar eclipse - magnitude and albedo

    Hello, everyone. On physics Olympiad in our country I get a interesting example... But, I didn't know how to solve it. Can you tell me how? It is known that the Moon when it is full has the apparent magnitude of approximately -12 mag and the Sun during the day has the apparent magnitude of...