Lunar limb

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The lunar limb is the edge of the visible surface (disc) of the Moon as viewed from Earth. [1] Libration of the Moon, with its irregular surface, leads to small changes in its profile; this complicates the task of precisely calculating eclipse times and durations. [2] However, data from the mapping of the lunar surface allows astronomers to predict the lunar profile for any given time with a high degree of certainty. [3] The irregularity of the lunar limb is the cause of Baily's beads collimated rays of sunlight that shine through in some places, and not in others, during a solar eclipse.

Moon Earths natural satellite

The Moon, also known as Luna, is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits. The Moon is after Jupiter's satellite Io the second-densest satellite in the Solar System among those whose densities are known.

Earth Third planet from the Sun in the Solar System

Earth is the third planet from the Sun, and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.

Libration perceived oscillating motion of orbiting bodies relative to each other

In astronomy, libration is the wagging of the Moon perceived by Earth-bound observers caused by changes in their perspective. It permits an observer to see slightly different halves of the surface at different times. It is similar in both cause and effect to the changes in the Moon's apparent size due to changes in distance. It is caused by three mechanisms detailed below, two of which are causing a relatively tiny physical libration via tidal forces exerted by the Earth. Such true librations are known as well for other moons with locked rotation.

The contrast of a brightly illuminated limb against a black sky makes it a popular target when testing telescope and binocular optics.

Telescope Optical instrument that makes distant objects appear magnified

A telescope is an optical instrument that makes distant objects appear magnified by using an arrangement of lenses or curved mirrors and lenses, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses. They were used for both terrestrial applications and astronomy.

Binoculars pair of telescopes mounted side-by-side

Binoculars or field glasses are two telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes when viewing distant objects. Most are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal mounted military models.

Optics The branch of physics that studies light

Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.

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Eclipse astronomical event where one body hides another

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. 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 or a transit.

Lunar eclipse when the Moon passes directly behind the Earth

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, 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.

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.

The saros is a period of approximately 223 synodic months, 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.

Occultation event that occurs when one object is hidden by another object that passes between it and the observer

An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. 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.

The Baily's beads effect, or diamond ring effect, is a feature of total and annular solar eclipses. As the Moon covers the Sun during a solar eclipse, the rugged topography of the lunar limb allows beads of sunlight to shine through in some places while not in others. The effect is named after Francis Baily, who explained the phenomenon in 1836. The diamond ring effect is seen when only one bead is left, appearing as a shining "diamond" set in a bright ring around the lunar silhouette.

Near side of the Moon

The near side of the Moon is the lunar hemisphere that is permanently turned towards Earth, whereas the opposite side is the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth – a situation known as synchronous rotation, or tidal locking.

December 2009 lunar eclipse lunar eclipse

A partial lunar eclipse was visible on New Year's Eve, Thursday, December 31, 2009. It was the last and largest of four minor lunar eclipses in 2009. This lunar eclipse is also notable, because it occurred during a blue moon. The next eclipse on New Year's Eve and blue moon will occur on December 31, 2028.

September 1996 lunar eclipse

A total lunar eclipse took place on Friday, September 27, 1996, the second of two lunar eclipses in 1996, the first being on Thursday, April 4. This is the 41st member of Lunar Saros 127. The previous event is the September 1978 lunar eclipse. The next event is the October 2014 lunar eclipse.

April 2014 lunar eclipse total lunar eclipse in April 2014

A total lunar eclipse took place on April 15, 2014. It was the first of two total lunar eclipses in 2014, and the first in a tetrad. Subsequent eclipses in the tetrad are those of October 8, 2014, April 4, 2015, and September 28, 2015.

October 2014 lunar eclipse lunar eclipse

A total lunar eclipse took place on October 8, 2014. It is the second of two total lunar eclipses in 2014, and the second in a tetrad. Other eclipses in the tetrad are those of April 15, 2014, April 4, 2015, and September 28, 2015.

April 2015 lunar eclipse lunar eclipse

A total lunar eclipse took place on 4 April 2015. It is the former of two total lunar eclipses in 2015, and the third in a tetrad. Other eclipses in the tetrad are those of 15 April 2014, 8 October 2014, and 28 September 2015.

September 2015 lunar eclipse

A total lunar eclipse took place between September 27 and 28, 2015. It was seen on Sunday evening, September 27, in the Americas; while in Europe, Africa, and the Middle East, it was seen in the early hours of Monday morning, September 28. It was the latter of two total lunar eclipses in 2015, and the final in a tetrad. Other eclipses in the tetrad are those of April 15, 2014, October 8, 2014, and April 4, 2015.

January 2018 lunar eclipse total lunar eclipse that occurred on January 31, 2018

A total lunar eclipse occurred on January 31, 2018. The Moon was near its perigee on January 30 and as such may be described as a "supermoon". The previous supermoon lunar eclipse was in September 2015.

January 2019 lunar eclipse

A total lunar eclipse occurred on January 21, 2019 UTC. For observers in the Americas, the eclipse took place between the evening of Sunday, January 20 and the early morning hours of Monday, January 21. For observers in Europe and Africa, the eclipse occurred during the morning of January 21. The Moon was near its perigee on January 21 and as such can be described as a "supermoon".

December 1964 lunar eclipse

A total lunar eclipse took place on December 19, 1964. A shallow total eclipse saw the Moon in relative darkness for 58 minutes and 54 seconds. The Moon was 17% of its diameter into the Earth's umbral shadow, and should have been significantly darkened. The partial eclipse lasted for 3 hours and 16 minutes in total. The eclipse afforded astrophysicist J. M. Saari the opportunity to make infrared pyrometric scans of the lunar surface with improved equipment, following up on Richard W. Shorthill's discovery of "hot spots" in the Tycho crater during the March 13, 1960 eclipse.

Gamma (eclipse) parameter of an eclipse that describes how centrally the shadow of the Moon or Earth strikes the other

Gamma 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.

Solar eclipse of December 26, 2038

A total solar eclipse will occur on December 26, 2038. 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.

Solar eclipses on the Moon

Solar eclipses on the Moon are caused when the Earth passes in front of the Sun, blocking its light. Viewers on Earth will see a lunar eclipse.

References

  1. "List of basic lunar features."
  2. O'Byrne, Chris. "Lunar Limb Corrections. Archived 2008-01-13 at the Wayback Machine "
  3. Watts, C. B. "The Marginal Zone of the Moon," Astron. Papers Amer. Ephem., 1963, 17, 1–951.