LRO and the September 27-28, 2015 Lunar Eclipse: Telescopic View

LEAD: Step outside on Sunday evening (September 27th) to see a special astronomical event: a supermoon total lunar eclipse. 1. At 9:07 p.m. EDT the moon will start to enter Earth’s shadow. An hour later, the moon will appear a ghostly copper color. The change in color will last for over an hour as the moon passes through Earth’s central shadow and is illuminated by filtered sunlight passing through Earth’s atmosphere. 2. As the moon orbits Earth, it has a farthest point in its orbit (apogee) and closest point (perigee). On Sunday, the full moon occurs during the closest perigee of the year. This is sometimes called a supermoon. 3. Supermoons occur *on average* every 14 months. But what’s special about Sunday’s supermoon is that it will happen during a total lunar eclipse. TAG: The next supermoon total lunar eclipse won't happen until 2033. For More InformationSee [http://eclipse.gsfc.nasa.gov/eclipse.html](http://eclipse.gsfc.nasa.gov/eclipse.html) Related pages

Interview with Noah Petro - LRO Deputy Project Scientist B-roll available for download referring to 2015 Supermoon and Eclipse. Interview (in Spanish) with NASA Scientist Irma Quispe NeiraFor complete transcript, click here. Interview with Jennifer Heldman - NASA ScientistFor complete transcript, click here. Lunar Reconnaissance Orbiter Deputy Project Scientist Noah Petro discusses the Sept. 27th supermoon eclipse and some of the cool things that scientists have learned about our moon.NASA will provide a LIVE FEED of Sunday's Supermoon eclipse. Click for details. For More InformationSee [http://www.nasa.gov/lro](http://www.nasa.gov/lro) Related pages

With the lunar horizon in the foreground, the Earth passes in front of the Sun, revealing the red ring of sunrises and sunsets along the limb of the Earth. The Earth and Sun are in Virgo for observers on the Moon. The bright star above them is beta Virginis.This video is also available on our YouTube channel. On September 28, 2015 Universal Time (the evening of the 27th for the Americas), the Moon enters the Earth’s shadow, creating a total lunar eclipse. When viewed from the Moon, as in this animation, the Earth hides the Sun. A red ring, the sum of all Earth’s sunrises and sunsets, lines the Earth’s limb and casts a ruddy light on the lunar landscape. With the darkness of the eclipse, the stars come out.The city lights of North and South America and of western Europe and Africa are visible on the night side of the Earth. The part of the Earth visible in this animation is the part where the lunar eclipse can be seen. Related pages

The geometry of the Moon's orbit in motion, from the end of August until the supermoon eclipse on September 27-28, 2015. The inner blue circle shows perigee distance, the outer blue circle shows apogee distance, and the off-center, light gray circle shows the Moon's orbit. Frame sequences with alpha channel are available for the separate elements of the animation.This video is also available on our YouTube channel. A simpler version of the animation, showing the Moon's orbital motion from apogee on September 14 to the perigee Full Moon and total lunar eclipse on September 27-28. The osculating eccentricity of the Moon's orbit during 2015. On September 28, 2015 (the night of the 27th in many places), the Moon will be full at the same time that it is closest to Earth for the year, a coincidence sometimes called a supermoon. As it happens, this largest Full Moon occurs within the Earth's shadow, creating the added spectacle of a total lunar eclipse.The Moon's orbit is very slightly elliptical and therefore somewhat off-center relative to the Earth. Each month, the Moon passes through points in its orbit called perigee and apogee, the closest and farthest points from the Earth for that month. Some perigees are a little closer than others. The closest perigee for 2015 occurs on September 28 at around 1:52 Universal Time, when the Moon will be 356,877 kilometers (221,753 miles) away. This is only an hour before the time of peak full Moon at 2:51 UT, when the Moon's ecliptic longitude differs from the Sun's by exactly 180 degrees.All of this takes place during a total lunar eclipse. The Moon makes first contact with the umbra, the central part of the Earth's shadow, at 1:07 UT, and it doesn't completely emerge until 4:27 UT.If we define a supermoon as a Full Moon that coincides with the closest perigee in a given year, then supermoons occur every 14 months, with occasional skips. The anomalistic month — the time between two perigees — is two days shorter than the cycle of phases, called the synodic month; the perigees "lap" the phases after 14 months.Total lunar eclipses involve a third cycle, the draconic month. The Moon's tilted orbit crosses the Earth-Sun plane at one of two points called nodes; a draconic month is the time it takes the Moon to return to the same node. Total lunar eclipses happen when a node crossing coincides with a Full Moon. Only then does the Moon's orbit carry it close enough to the Earth-Sun line to actually pass through the shadow cast by the Earth.A supermoon eclipse requires the alignment of all three cycles, the synodic, anomalistic, and draconic months, and this happens every 18 years 11 days, a period known as a saros. Eclipses separated by this period tend to share certain properties and are grouped into families, or saros series. The 2015 supermoon eclipse is the first in Saros 137. There will be seven more supermoon eclipses in this series, the last in December of 2141.The animation begins at the end of August showing that perigee and Full Moon miss each other by about a day. It then shows apogee on September 14, when the Moon is almost 32 Earth diameters away. It ends on September 28, the day of the supermoon eclipse, when the distance to the Moon is 28 Earth diameters. The Moon graphic in the upper left shows the change in the Moon's apparent size as it moves closer and farther in its orbit, as well as its copper color during the eclipse. The relative sizes of the Earth and Moon in the main orbit graphic are exaggerated by a factor of 15 to make them more easily visible. EccentricityThe farthest apogee of 2015 occurs on September 14, when the Moon is 406,472 kilometers (252,257 miles) away. The ratio of the apogee to the perigee,ra / rp = 1.139 is the basis of the statement that the Moon's distance and apparent diameter vary by 14%.In principle, this ratio can also be used to calculate the oblongness or eccentricity of the Moon's elliptical orbit.e = 1 − 2 / (( ra / rp ) + 1 ) Plugging in the closest perigee and the farthest apogee, we get an eccentricity e = 0.065. Can that be right? Most references (this NASA one, for example) say that for the Moon, e = 0.055. What's going on here?As it turns out, the Moon's e isn't constant! It's changing all the time, mostly due to the strong influence of the Sun's gravity. The value given in references is a long-term average. During 2015, as the following graph shows, the eccentricity varies from a low of e = 0.0283 in June to a high of e = 0.0747 on the night of the supermoon eclipse. There are two major cycles apparent in the graph, one with a period of roughly a month (31.8 days) and the other repeating about every half-year (205.9 days). Both of these cycles arise from the orientation of the Moon's orbit with respect to the Sun.The graph is based on an expression for the varying or osculating eccentricity in (Simon et al. 1994). Note that the calculation we did earlier, using the closest perigee and the farthest apogee, isn't physically valid, since these occur at two different points in time. For More InformationSee [2015 Lunar Eclipse Gallery](http://svs.gsfc.nasa.gov/Gallery/SupermoonLunarEclipseSeptember2015.html) Related pages

Universal Time (UT). The Moon moves right to left, passing through the penumbra and umbra, leaving in its wake an eclipse diagram with the times at various stages of the eclipse. Eastern Daylight Time (EDT). The Moon moves right to left, passing through the penumbra and umbra, leaving in its wake an eclipse diagram with the times at various stages of the eclipse. Central Daylight Time (CDT). The Moon moves right to left, passing through the penumbra and umbra, leaving in its wake an eclipse diagram with the times at various stages of the eclipse. Mountain Daylight Time (MDT). The Moon moves right to left, passing through the penumbra and umbra, leaving in its wake an eclipse diagram with the times at various stages of the eclipse. Pacific Daylight Time (PDT). The Moon moves right to left, passing through the penumbra and umbra, leaving in its wake an eclipse diagram with the times at various stages of the eclipse. The Moon moves right to left, passing through the penumbra and umbra, at 10 seconds per frame. Frames include an alpha channel. The star field that appears behind the Moon during the eclipse. The Moon is in Pisces. Because of the narrow field of view, no easily recognized stars are visible here. The brightest star, HR 67 (or HIP 1421), is magnitude 6.2, visible only to the keenest eyes in an especially dark location. On the evening of September 27, 2015 in the Americas (early morning on September 28 in Europe and most of Africa), the Moon enters the Earth’s shadow, creating a total lunar eclipse, the last of four visible in the Western Hemisphere in a span of 18 months. This animation shows the changing appearance of the Moon as it travels into and out of the Earth’s shadow, along with the times at various stages. Versions of the animation have been created for each of the four time zones of the contiguous United States, as well as one for Universal Time.All of South America and most of North and Central America will see the entire eclipse, while those west of roughly 120°W will see it in progress at moonrise. You won’t need special equipment to see it. Just go outside and look up!The penumbra is the part of the Earth’s shadow where the Sun is only partially covered by the Earth. The umbra is where the Sun is completely hidden. The Moon's appearance isn't affected much by the penumbra. The real action begins when the Moon starts to disappear as it enters the umbra at about 9:07 Eastern Daylight Time. An hour later, entirely within the umbra, the Moon is a ghostly copper color, and this lasts for over an hour before the Moon begins to emerge from the central shadow.The view in these animations is geocentric. Because of parallax, the Moon's position against the background stars will look a bit different for observers at different locations on the surface of the Earth. The Moon is in the southwestern part of the constellation Pisces. For More InformationSee [2015 Lunar Eclipse Gallery](http://svs.gsfc.nasa.gov/Gallery/SupermoonLunarEclipseSeptember2015.html) Related pages

Waxing crescent. Visible toward the southwest in early evening. First quarter. Visible high in the southern sky in early evening. Waxing gibbous. Visible to the southeast in early evening, up for most of the night. Full Moon. Rises at sunset, high in the sky around midnight. Visible all night. Waning gibbous. Rises after sunset, high in the sky after midnight, visible to the southwest after sunrise. Third quarter. Rises around midnight, visible to the south after sunrise. Waning crescent. Low to the east before sunrise. New Moon. By the modern definition, New Moon occurs when the Moon and Sun are at the same geocentric ecliptic longitude. The part of the Moon facing us is completely in shadow then. Pictured here is the traditional New Moon, the earliest visible waxing crescent, which signals the start of a new month in many lunar and lunisolar calendars. The phase and libration of the Moon for 2015, at hourly intervals. Includes supplemental graphics that display the Moon's orbit, subsolar and sub-Earth points, and the Moon's distance from Earth at true scale. Craters near the terminator are labeled. The phase and libration of the Moon for 2015 at hourly intervals, with music, titles, and supplemental graphics. The music is "Migrating Birds" from Killer Tracks Production Music, composed by Brice Davoli. The phase and libration of the Moon for 2015, at hourly intervals. The higher resolution frames include an alpha channel. The phase and libration of the Moon for 2015, with music and titles. The music is "Migrating Birds" from Killer Tracks Production Music, composed by Brice Davoli. The orbit of the Moon in 2015, viewed from the north pole of the ecliptic, with the vernal equinox to the right. The sizes of the Earth and Moon are exaggerated by a factor of 25 (420 x 420) or 15 (1080 x 1080). The frames include an alpha channel. An animated diagram of the subsolar and sub-Earth points for 2015. The Moon's north pole, equator, and meridian are indicated. The frames include an alpha channel. An animated diagram of the Moon's distance from the Earth for 2015. The sizes and distances are true to scale, and the lighting and Earth tilt are correct. The frames include an alpha channel. Crater labels. The labels appear when the center of the crater is within 20 degrees of the terminator (the day-night line). They are on the western edge of the crater during waxing phases (before Full Moon) and to the east during waning phases. The frames include an alpha channel. Dial-A-Moon New: Click on the image to download a high-resolution version with labels for craters near the terminator. The data in the table for the entire year can be downloaded as a JSON file or as a text file.The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2015, at hourly intervals. Until the end of 2015, the initial Dial-A-Moon image will be the frame from this animation for the current hour.More in this series:Moon Phase and Libration GalleryLunar Reconnaissance Orbiter (LRO) has been in orbit around the Moon since the summer of 2009. Its laser altimeter (LOLA) and camera (LROC) are recording the rugged, airless lunar terrain in exceptional detail, making it possible to visualize the Moon with unprecedented fidelity. This is especially evident in the long shadows cast near the terminator, or day-night line. The pummeled, craggy landscape thrown into high relief at the terminator would be impossible to recreate in the computer without global terrain maps like those from LRO.The Moon always keeps the same face to us, but not exactly the same face. Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it's wobbling. This wobble is called libration.The word comes from the Latin for "balance scale" (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides. The sub-Earth point gives the amount of libration in longitude and latitude. The sub-Earth point is also the apparent center of the Moon's disk and the location on the Moon where the Earth is directly overhead.The Moon is subject to other motions as well. It appears to roll back and forth around the sub-Earth point. The roll angle is given by the position angle of the axis, which is the angle of the Moon's north pole relative to celestial north. The Moon also approaches and recedes from us, appearing to grow and shrink. The two extremes, called perigee (near) and apogee (far), differ by more than 10%.The most noticed monthly variation in the Moon's appearance is the cycle of phases, caused by the changing angle of the Sun as the Moon orbits the Earth. The cycle begins with the waxing (growing) crescent Moon visible in the west just after sunset. By first quarter, the Moon is high in the sky at sunset and sets around midnight. The full Moon rises at sunset and is high in the sky at midnight. The third quarter Moon is often surprisingly conspicuous in the daylit western sky long after sunrise.Celestial north is up in these images, corresponding to the view from the northern hemisphere. The descriptions of the print resolution stills also assume a northern hemisphere orientation. (There is also a south-up version of this page.) From this birdseye view, it's somewhat easier to see that the phases of the Moon are an effect of the changing angles of the sun, Moon and Earth. The Moon is full when its orbit places it in the middle of the night side of the Earth. First and Third Quarter Moon occur when the Moon is along the day-night line on the Earth.The First Point of Aries is at the 3 o'clock position in the image. The sun is in this direction at the spring equinox. You can check this by freezing the animation at the 1:03 mark, or by freezing the full animation with the time stamp near March 20 at 23:00 UTC. This direction serves as the zero point for both ecliptic longitude and right ascension.The north pole of the Earth is tilted 23.5 degrees toward the 12 o'clock position at the top of the image. The tilt of the Earth is important for understanding why the north pole of the Moon seems to swing back and forth. In the full animation, watch both the orbit and the "gyroscope" Moon in the lower left. The widest swings happen when the Moon is at the 3 o'clock and 9 o'clock positions. When the Moon is at the 3 o'clock position, the ground we're standing on is tilted to the left when we look at the Moon. At the 9 o'clock position, it's tilted to the right. The tilt itself doesn't change. We're just turned around, looking in the opposite direction. The subsolar and sub-Earth points are the locations on the Moon's surface where the sun or the Earth are directly overhead, at the zenith. A line pointing straight up at one of these points will be pointing toward the sun or the Earth. The sub-Earth point is also the apparent center of the Moon's disk as observed from the Earth.In the animation, the blue dot is the sub-Earth point, and the yellow dot is the subsolar point. The lunar latitude and longitude of the sub-Earth point is a measure of the Moon's libration. For example, when the blue dot moves to the left of the meridian (the line at 0 degrees longitude), an extra bit of the Moon's western limb is rotating into view, and when it moves above the equator, a bit of the far side beyond the north pole becomes visible.At any given time, half of the Moon is in sunlight, and the subsolar point is in the center of the lit half. Full Moon occurs when the subsolar point is near the center of the Moon's disk. When the subsolar point is somewhere on the far side of the Moon, observers on Earth see a crescent phase. The Moon's orbit around the Earth isn't a perfect circle. The orbit is slightly elliptical, and because of that, the Moon's distance from the Earth varies between 28 and 32 Earth diameters, or about 356,400 and 406,700 kilometers. In each orbit, the smallest distance is called perigee, from Greek words meaning "near earth," while the greatest distance is called apogee. The Moon looks largest at perigee because that's when it's closest to us.The animation follows the imaginary line connecting the Earth and the Moon as it sweeps around the Moon's orbit. From this vantage point, it's easy to see the variation in the Moon's distance. Both the distance and the sizes of the Earth and Moon are to scale in this view. In the full-resolution frames, the Earth is 50 pixels wide, the Moon is 14 pixels wide, and the distance between them is about 1500 pixels, on average.Note too that the Earth appears to go through phases just like the Moon does. For someone standing on the surface of the Moon, the sun and the stars rise and set, but the Earth doesn't move in the sky. It goes through a monthly sequence of phases as the sun angle changes. The phases are the opposite of the Moon's. During New Moon here, the Earth is full as viewed from the Moon. Related pages