DOCSLIB.ORG

Types of Eclipses Earth

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Types of Eclipses Earth A Digital Supplement to Astronomy Insights Astronomy Magazine © 2017 Kalmbach Publishing Co. Prepare for Totality Get Ready for the August 21 Total Solar Eclipse June 2017 • Astronomy.com 1 READ UP Research solar eclipses. Try Frank Close’s Eclipse: Journeys to the Dark Side of the Moon or Totality: The Great American Eclipses of 2017 and 2024 by Mark Littmann and Fred Espenak. 2 CHOOSE YOUR SPOT If you haven’t already done so, you may be a little late to secure a flight or hotel room in or near the totality band. However, even if you can’t quite reach “the zone,” there’s still lots to see even in the partial eclipse areas. 3 GET YOUR GEAR Got your EclipSmart Solar Shades, Solar Glasses, or solar optical products yet? Don’t wait ‘til the last minute to obtain these crucial pieces of solar viewing equipment. 4 PREPARE YOUR CAMERA If you’re planning to record images or video of the eclipse, you’ll want to be sure you have the right Solar Safe protection – like the EclipSmart Photo Filter - for your camera and smart phone. 5 PRACTICE IN ADVANCE The experience of a solar eclipse can be overwhelming. Determining what you want to do in advance and “going through the motions” beforehand will help prevent something important from being forgotten. Remember, with solar eclipses, there are no “do-overs.” celestron.com/eclipsewatch2017 1. CAN’T WATCH IT IN PERSON? 6. WATCH THE SHADOWS. Watch it live via the Crescent Sun shadows can appear Lowell Observatory’s feed. as sunlight filters through tree leaves; moving shadow bands may be visible on flat pale surfaces just before and WATCH IT LIVE after totality. 2. GO FOR A RUN. Sign up 7. SEE THE ENTIRE ECLIPSE. and complete the Virtual Running Watch the Moon transit the Sun. Club’s Total Solar Eclipse 5K/10K and you could win a Celestron telescope. REGISTER HERE 3. KEEP HYDRATED and 8. DURING TOTALITY, wear plenty of sunblock. Even look towards the horizon and during the partial phases of the witness a 360° sunrise/sunset. eclipse, the Sun’s rays, can still burn your skin. 4. BE MOBILE. Weather can 9. ENJOY the sheer beauty of the change quickly, so be prepared to eclipse, so you can create your own move to clear skies if necessary. memorable experience. Read about Celestron’s Kevin Kawai’s, search of The Elusive Ring of Fire. 5. DON’T FIXATE ON THE SKY. 10. PAUSE FOR A MOMENT Air temperature changes as the to think of what ancient people eclipse progresses, animals can must have thought during behave curiously; take notice. an eclipse when the Sun disappeared from the sky. celestron.com/eclipsewatch2017 Solar eclipse geometry August 21, the dark inner part of the Moon’s shadow will sweep across What’s happening in the United States, creating a total solar eclipse for regions in 14 states. ON But, you may ask, the Sun is so much larger than the Moon, so how does space and on Earth. this work? While our daytime star has a diameter about 400 times larger than that by Michael E. Bakich; of the Moon, it also lies roughly 400 times farther away. This means both disks appear to be the same size, so at certain times from certain locations, the Moon illustrations by Roen Kelly can completely cover the Sun. Be sure to protect your eyes during the partial phases. The simplest way is to buy a pair of solar viewing glasses. Wear them even when 99 percent of the Sun is covered because the remaining part is still intense enough to cause retinal burns. But remember: During the 2 minutes and 40 seconds of totality, remove any solar filters, or you’ll miss the most spectacular part of the eclipse. Path of totality Umbra Greatest eclipse Penumbra Moon Types of eclipses Earth Total eclipse The Sun behind the Moon Moon’s changing distance Moon Earth Sun Top view Annular eclipse Perigee Apogee 225,300 miles 251,900 miles (362,600 km) (405,400 km) Partial eclipse Moon’s orbital tilt Side view 5.14° Top: Some central eclipses are total and others annular because the Moon’s The three main types of solar eclipses are total, where the Moon distance from Earth changes. Bottom: An completely covers the Sun’s surface; annular, during which the Moon eclipse doesn’t happen every New Moon lies too far from Earth (or Earth too far from the Sun) for it to cover the because our satellite’s orbit tilts more Sun completely; and partial, where the lineup isn’t exact and only the than 5° from the plane of our orbit. Moon’s outer shadow touches our planet. When can eclipses happen? The Moon’s tilted orbit intersects Plane of our orbit around the Sun only the Moon’s twice in each revolution at points orbit New Moon called nodes. Only when the Moon Moon’s orbit lies at one of the nodes can an New eclipse (solar or lunar) occur. New Sun Moon Moon Line of nodes point to the Sun New Moon Earth’s orbit Two types of shadows If the Sun were a point source, like one of the nighttime stars, the Moon would cast only one kind of shadow. Instead, the Sun stretches 0.5° across, so even during total solar eclipses, some of its light passes either above or Path of totality below the Moon, creating a less-dense shadow called the penumbra. Only Umbra where the Moon blocks all the light from the Sun — in its dark inner shadow called the umbra — can people on Earth see a total solar eclipse. Anywhere Greatest eclipse in the penumbra, the eclipse will be partial, but the percentage of the Sun covered will increase as you get near the umbra. Unfortunately, the umbra Penumbra Moon is small, no more than a hundred miles in diameter. On the other hand, the penumbra measures more than 4,000 miles across. Earth TotalSolar eclipses solar for the eclipses next 15 years during the next 20 years A u 2 g 0 . 2 1 6 2 , 3 A 3 u 0 g 2 , u 0 s t 3 Left: From now until the end of h 1 rc 2 a , 2037, 12 total solar eclipses will M 2 0 occur. This map shows the paths 2 gust 21 6 Au , 2017 of totality in orange and each September 2, 203 eclipse’s center line in black. 5 Below: This sequence shows an 4 2 entire total eclipse in 11 images. Se 0 A p 2 4 u t. 2 , 3 gu The center shows totality, while , 20 l 8 20 s 35 ri 0, t p arch 2 2, the two diamond rings flank it. A M 20 27 BEN COOPER/LAUNCHPHOTOGRAPHY.COM July 22, 202 July 2, 2 8 019 20 N 037 20 ov 3, 2 Michael E. Bakich is a senior 4 , em 1 r 1 be uly mbe r 2 J editor of Astronomy who Dece 5, 203 0 will be hosting the world’s Center line D 2 e largest eclipse event August 21 0 c 2 . Path of totality 1 4 at Rosecrans Memorial Airport , in St. Joseph, Missouri. SOLAR ECLIPSE 2017 All stories by Michael E. Bakich Observe from the center line An extra minute of totality is worth almost anything you have to do to get it. n all likelihood, the most curved lines on it. The two outer important thing you’ll read ones show the northern and or hear about the August 21, southern limits of totality. 2017, eclipse is that you must Within their borders is where Iget to the path of totality. It’s the Moon’s umbra — its dark true. As I like to say in my talks, inner shadow — falls on Earth. the difference between viewing And just like your art teacher a partial eclipse and experienc- told you in third grade: Stay ing a total one is the difference inside the lines. between almost dying and dying But it’s the line midway — there’s no comparison. between those two extremes Once you’ve decided to adopt that’s most important. Astron- this sage advice, consider going omers call this the center line for one step further: Try your best to obvious reasons. It’s along this position yourself on the eclipse’s path that the central part of the center line. Any detailed map Moon’s shadow falls, and that’s that shows the path of the 2017 where you should try to be on total solar eclipse will have three eclipse day. Rehearse for eclipse day Here’s how to do an actual run-through months before August 21, 2017. s you read this, of our planet’s axis points toward America’s eclipse is a the Sun, it’s the Northern Hemi- year away. But people sphere’s summer. When the are beginning to get southern tip points sunward, the Anervous already. They ask ques- Northern Hemisphere experi- tions, start making plans. The ences winter. Spring and autumn “hands-on” folks desire a bit lie midway between these more, however. They want to get extremes. All seasons reverse in out under the daytime sky and the Southern Hemisphere. check out the circumstances Because of the tilt, the Sun’s themselves. If you’re one of them, maximum altitude at any location I have good news: There’s a way changes by 47° in the six-month to conduct an accurate rehearsal span from June to December or for the eclipse.
Load more

Recommended publications
  • Illuminating Eclipses: Astronomy and Chronology in King Lear
    Brief Chronicles Vol. II (2010) 32 Illuminating Eclipses: Astronomy and Chronology in King Lear Hanno Wember ohann Gottfried Herder wrote his famous essay Shakespeare in 1772. He was (as Wieland, Lessing and, of course, Goethe and Schiller) one of the 18th century German writers “who first embraced Shakespeare and welcomed his Jgenius as a dramatist.”1 In his 1980 introduction to Herder’s essay, Konrad Nussbächer wrote: “Shakespeare is not, as it appeared in the 18th century, a natural genius growing up in the wild, but a highly cultured, artful Renaissance poet and practitioner of the stage.” Astronomy was one of the liberal arts and sciences a “highly cultured” man of Renaissance England was expected to know. This essay will review a few illuminating examples of Shakespeare’s profound knowledge of astronomy, and will examine a new astronomical reference that could shed significant new light on Shakespearean chronology. Shakespeare’s Astronomy In many regards Shakespeare had a better knowledge of the relationship between the moon and the tides2 than his distinguished contemporary Galileo (1564 - 1642), who tried to explain the tides by the two motions of the earth, correlating to the day and the year.3 This was an erroneous explanation for ebb and flow. But while Galileo refused to acknowledge any tidal influence of the moon, Bernardo knew better, referring to the moon as the Brief Chronicles Vol. II (2010) 33 moist star Upon whose influence Neptune’s empire stands (Hamlet, I.1.135)4 To Prince Henry, likewise, the moon commands the tides: The fortune of us that are moon’s men doth ebb and flow like the sea, being governed as the sea is by the moon…..Now in as low an ebb as the foot of the ladder, and by and by in as high a flow as the ridge of the gallows.
    [Show full text]
  • Occdhtlm3newstelter
    OccdhtlM3Newstelter Volume II, Number 10 january, 1981 Occultation Newsletter is published by the International Occultation Timing Association. Editor and Compositor: H. F. DaBo11; 6 N 106 White Oak Lane; St. Charles, IL 60174; U.S.A. Please send editorial matters to the above, but send address changes, requests, matters of circulation, and other IOTA business to IOTA; P.0. Box 596; Tinley Park; IL 60477; U.S.A. NOTICE TO LUNAR OCCULTATION OBSERVERS paho1. by contacting Sr. Francisco Diego Q., Ixpan- tenco 26-bis, Real dc Ids Reyes, Coyoacdn, Mexico, L. V. Morrison D.F., Mexico. Currently, however, the Latin American Section is experiencing problems with funding, and On 1981 January 1 the international centre for the for the time being, it may be necessary for would-be receipt of timings of occultations of stars by the IOTA/LAS members to subscribe to the English-lan- Moon will be transferred from HM Nautical Almanac guage edition of o.n., or to join the parent IOTA. Office, Royal Greenwich Observatory, England to As- tronomical Division, Hydrographic Department, Japan IOTA NEWS "' From that date observers should send their lunar oc- cultation reports and any correspondence connected David W. Dunham with lunar occultations to the following address: As of 1981 January 1, H. M. Nautical Almanac Office, Astronomical Division at the Royal Greenwich Observatory, England, will Hydrographic Department discontinue collecting observations of lunar occul- Tsukiji-5 tations. After that date, observers should send Chuo-ku, Tokyo their reports to the new International Occultation 104 JAPAN Centre in japan, as described in this issue's lead article.
    [Show full text]
  • Variation of Secondary Cosmic Gamma Ray Flux During Lunar Eclipse
    Variation of secondary cosmic gamma ray flux during lunar eclipse S. Roy* , S. Chatterjee , S. Chakraborty** , S. Biswas , S. Das , S. K. Ghosh , S. Raha Department of Physics (CAPSS), Bose Institute, Kolkata, India. E-mail: [email protected] Introduction Astronomical events such as Solar eclipses and Lunar eclipses provide the opportunity for studying the disturbance produced in the atmosphere and its effect on cosmic ray intensity. There are earlier reports on decrease in secondary cosmic gamma ray (SCGR) flux during solar eclipse and enhancement of the same during lunar eclipse [1-4]. We have measured the variation of SCGR flux during two lunar eclipses that took place in India in the year 2018, one on 31st of January and the other on 27th of July. Both the measurements have been carried out in the Detector laboratory of Bose Institute, Kolkata, India, using NaI (Tl) scintillator detector. We observed slight increment of SCGR during the lunar eclipse of January. We did not observe any significant changes in SCGR during lunar eclipse of July. Experimental Setup ❖ NaI(Tl) scintillator detector is used. Size of the crystal: 5.1cm × 5.1cm ❖ Gamma ray sources used for detector calibration: 137Cs (662 keV), ❖ PMT bias: +600V. Signals are amplified and shaped before sending 60Co (1173 keV and 1332 keV) and 22Na (551 keV) them to MCA for energy spectrum accumulation ORTEC-556 ORTEC-671 Schematic of the signal processing electronics Picture of the experimental setup Gamma ray spectra with different configurations of lead shielding ADC
    [Show full text]
  • Glossary of Marine Navigation 798
    GLOSSARY OF MARINE NAVIGATION 798 The main cause, however, appears to be the winds which prevail from south through west to northwest over 50 percent of the time throughout the year and the transverse flows from the English coast toward the Skaggerak. The current retains the characteristics of a J major nontidal current and flows northeastward along the northwest coast of Denmark at speeds ranging between 1.5 to 2.0 knots 75 to 100 percent of the time. Jacob’s staff. See CROSS-STAFF. jamming, n. Intentional transmission or re-radiation of radio signals in such a way as to interfere with reception of desired signals by the K intended receiver. Janus configuration. A term describing orientations of the beams of acoustic or electromagnetic energy employed with doppler naviga- Kaléma, n. A very heavy surf breaking on the Guinea coast during the tion systems. The Janus configuration normally used with doppler winter, even when there is no wind. sonar speed logs, navigators, and docking aids employs four beams Kalman filtering. A statistical method for estimating the parameters of a of ultrasonic energy, displaced laterally 90° from each other, and dynamic system, using recursive techniques of estimation, mea- each directed obliquely (30° from the vertical) from the ship’s bot- surement, weighting, and correction. Weighting is based on vari- tom, to obtain true ground speed in the fore and aft and athwartship ances of the measurements and of the estimates. The filter acts to directions. These speeds are measured as doppler frequency shifts reduce the variance of the estimate with each measurement cycle.
    [Show full text]
  • Lunar Nodes Keys to Emotions and Life Experience
    Lunar Nodes Keys To Emotions and Life Experience Diane Ronngren Copyright 2012 ETC Publishing All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying or recording, or by any information storage and retrieval system without written permission from the author and publisher, except in the case of brief quotations embodied in critical reviews and articles. ETC Publishing www.etcpublishing.com ISBN 978 -1-930038-55-4 Cover design and graphics by Gary Dunham Dedication To my mother, Norma, who gave me life, taught me the values inherent in my South Node in Libra and inspired me to pursue the possibilities of my North Node in Aries. To Family, who have always encouraged my life journey. Table of Contents Introduction ......................................................................................7 Chapter 1 - Symbols of Destiny ........................................................ 9 Chapter 2 - Node Basics .................................................................. 20 Chapter 3 - Lunar Nodes, Signs and Houses .................................. 26 Aries North Node / Libra South Node ....................................... 26 1st House North Node / 7th House South Node Taurus North Node / Scorpio South Node ................................. 29 2nd House North Node / 8th House South Node Gemini North Node / Sagittarius South Node ........................... 33 3rd House North Node / 9th House South Node Cancer North Node / Capricorn South Node ............................. 36 4th House North Node / 10th House South Node Leo North Node / Aquarius South Node .................................... 39 5th House North Node / 11th House South Node Virgo North Node / Pisces South Node ..................................... 42 6th House North Node / 12th House South Node Libra North Node / Aries South Node ....................................... 45 7th House North Node / 1st House South Node Scorpio North Node / Taurus South Node ................................
    [Show full text]
  • Solar Eclipses, One of Nature’S Most Impressive Sights, Have Fascinated People for Thousands of Years
    ® World Book Student Database The trusted, student-friendly online reference tool. Name: ____________________________________________________ Date:_________________ World Book Online: Solar eclipses, one of nature’s most impressive sights, have fascinated people for thousands of years. How much do you know about solar eclipses? Answer these questions to find out! Solar Eclipse First, go to www.worldbookonline.com Then, click on “Student.” If prompted, log on with your ID and Password. Find the answers to the questions below by using the “Search” tool. Since this activity is about solar eclipses, you can start by searching the key word “eclipse.” Write the answers on the lines provided or below the question. Find1. A It! solar eclipse takes place when the sun appears to become dark as the _______________ passes between the sun and Earth. 2. A _______________ eclipse occurs when the moon darkens as it passes through Earth’s shadow. 3. During a solar eclipse the moon’s shadow usually moves from west to east across Earth at a speed of about _______________ miles ( _______________ kilometers) per hour. 4. What is the average time the sun is totally darkened during a total solar eclipse? 5. A total solar eclipse can be seen only in certain parts of the world, which lie in the __________________________. © 2017 World Book, Inc. Chicago, Illinois, U.S.A. All rights reserved. World Book and the globe device are trademarks or registered trademarks of World Book, Inc. This webquest may be reproduced without World Book’s permission provided that it is reproduced exactly as published by World Book and is reproduced for entirely non-commercial educational purposes.
    [Show full text]
  • Looking at Eclipses from Both Sides
    Firefox https://cdn.mc-weblink.sg-mktg.com/weblink/MTYyMzAzOTc5N3xKe... Email not displaying correctly? View it in your browser. Looking at Eclipses from Both Sides by Zane B Stein If you have looked at eclipses astrologically you may have noticed a strange fact: the time that astronomers list for the time of maximum eclipse is usually different than the one your astrology program gives you, and sometimes the difference can be quite a few minutes. Why is that? We can give you a clear explanation, and then we can show you how you can adjust a setting (in both Solar Fire, and Astro Gold for Mac), so that you can calculate the charts for the times of both the astrological and the astronomical eclipses. 1 of 4 6/7/2021, 11:18 AM Firefox https://cdn.mc-weblink.sg-mktg.com/weblink/MTYyMzAzOTc5N3xKe... Let’s begin by comparing the eclipse definitions. Astronomical Definition: According to NASA, "An eclipse occurs when one heavenly body such as a moon or planet moves into the shadow of another heavenly body." During a Lunar Eclipse, the “Earth moves between the Sun and the Moon, Earth blocks the sunlight instead of light hitting the Moon's surface, and Earth's shadow falls on the Moon," but if it is a Solar Eclipse, “the Moon moves between the Sun and Earth, the Moon blocks the light of the Sun instead of light hitting the Earth's surface, and the Moon's shadow falls on the Earth.” Astrological Definition: When the Sun and Moon are at the exact same degree, minute and second of a sign (New Moon) or opposite signs (Full Moon), AND the lunation occurs not far from the North or South Lunar Nodes, you have, respectfully, a Solar or Lunar Eclipse.
    [Show full text]
  • Viewing an Eclipse Safely
    ECLIPSES SOLAR an eclipse safely How to observe SOLAR ECLIPSE, OCTOBER 2014, BY LEMAN NORTHWAY Solar eclipses are quite rare and are often a major event. The SOLAR ECLIPSES Moon passes right in front of the Sun, blotting out its disc. Every time a solar eclipse occurs there are various things to look for. However, it is extremely dangerous to just go out and look up. The Sun is so bright that just looking at it can blind you, so you’ll need to prepare beforehand. There are various ways to observe eclipses safely, using both everyday materials and telescopes or binoculars. So read this leaflet Introduction to find out what happens during an eclipse and how you can see all the stages of the event safely. This booklet was written by the Royal Astronomical Society with The Society for Popular Astronomy and is endorsed by the British Astronomical Association The Royal Astronomical The Society for Popular Formed in 1890, the Society, founded in Astronomy is for British Astronomical 1820, encourages and beginners of all ages. Our Association has an promotes the study of aim is to make astronomy international reputation astronomy, solar-system fun, and our magazine, for the quality of science, geophysics and Popular Astronomy, is full its observational closely related branches of information to help and scientific work. of science. you get to know the Membership is open to www.ras.org.uk sky and get involved. We even have a special Young all persons interested in HIGGS-BOSON.COM JOHNSON: PAUL BY D Stargazers section, run by TV’s Lucie Green.
    [Show full text]
  • The Quarterly Magazine of the Thanet Branch of the Campaign for Real Ale
    Fourth Quarter 2018 Free ALE The Quarterly Magazine of the Thanet Branch of the Campaign for Real Ale Inside this issue: Hop hoddening AoT’s Brighton run Social secretary’s blog A long lunch in St Albans Enjoying the beers of Tallinn On the Thanet Loop bus route ALE of Thanet A view from the chair After two years in the chair, this will probably be my last offering to you, not because I haven’t enjoyed my time, but as I currently just have too much on my plate, and now feels the right time to pass the gavel on, although I will (hopefully) remain on the committee and in my role as the Beer Festival Organiser. We are a strong Branch with over 500 members, if one of those members is you, please come along to our Annual General Meeting to be held on Saturday 19th January 2019 at The Bradstow Mill, 11.45 for a 12:00 prompt start. This is your opportunity to becoming involved in your Branch, to help us move forward, to celebrate and enjoy the excellent Re- al Ale and Real Cider that some of our local amazing establishments. Aside from the Branch Committee, we are also specifically looking for someone who could put together the Beer Festival Programme, including seeking advertisers and arranging the printing – could this be you? One the difficult tasks I have had this year is working with the Beer Festival Committee to ensure that we have a Festival in 2019. We had been in a really lucky position that for a considerable time we have had a very, very good rate when we hired the Winter Gardens, and due to the situa- tion, they are in, they had to review our hire, and after much number crunching and negotiation we have managed to secure the venue.
    [Show full text]
  • Cislunar Tether Transport System
    FINAL REPORT on NIAC Phase I Contract 07600-011 with NASA Institute for Advanced Concepts, Universities Space Research Association CISLUNAR TETHER TRANSPORT SYSTEM Report submitted by: TETHERS UNLIMITED, INC. 8114 Pebble Ct., Clinton WA 98236-9240 Phone: (206) 306-0400 Fax: -0537 email: [email protected] www.tethers.com Report dated: May 30, 1999 Period of Performance: November 1, 1998 to April 30, 1999 PROJECT SUMMARY PHASE I CONTRACT NUMBER NIAC-07600-011 TITLE OF PROJECT CISLUNAR TETHER TRANSPORT SYSTEM NAME AND ADDRESS OF PERFORMING ORGANIZATION (Firm Name, Mail Address, City/State/Zip Tethers Unlimited, Inc. 8114 Pebble Ct., Clinton WA 98236-9240 [email protected] PRINCIPAL INVESTIGATOR Robert P. Hoyt, Ph.D. ABSTRACT The Phase I effort developed a design for a space systems architecture for repeatedly transporting payloads between low Earth orbit and the surface of the moon without significant use of propellant. This architecture consists of one rotating tether in elliptical, equatorial Earth orbit and a second rotating tether in a circular low lunar orbit. The Earth-orbit tether picks up a payload from a circular low Earth orbit and tosses it into a minimal-energy lunar transfer orbit. When the payload arrives at the Moon, the lunar tether catches it and deposits it on the surface of the Moon. Simultaneously, the lunar tether picks up a lunar payload to be sent down to the Earth orbit tether. By transporting equal masses to and from the Moon, the orbital energy and momentum of the system can be conserved, eliminating the need for transfer propellant. Using currently available high-strength tether materials, this system could be built with a total mass of less than 28 times the mass of the payloads it can transport.
    [Show full text]
  • 1986Aj 92.120Id the Astronomical Journal Volume 92, Number 5 November 1986 Modeling Pluto-Charon Mutual Eclipse Events. I. First
    THE ASTRONOMICAL JOURNAL VOLUME 92, NUMBER 5 NOVEMBER 1986 92.120ID MODELING PLUTO-CHARON MUTUAL ECLIPSE EVENTS. I. FIRST-ORDER MODELS R. Scott Dunbar and Edward F. Tedesco Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 1986AJ Received 29 May 1986; revised 7August 1986 ABSTRACT We present numerical and analytical models describing the light curves resulting from mutual events between close planetary binaries, with particular application to the Pluto-Charon system. These models are referred to as “first-order” models because they incorporate the effects of shadowing in such sys- tems, in contrast to “zeroth-order” models, which do not include shadowing. The shadows cast between close binaries of similar size (as in the case of Pluto and Charon) can be treated as extensions of the eclipsing bodies themselves at small solar phase angles. Shadowing plays a major role in the morphology of mutual event light curves. The numerical approach is a straightforward, but computationally inten- sive, discrete-element integration. The analytical approach uses a conceptually simple model of three circular disks, representing the planet, satellite, and shadow, and computes the complex geometric relationship among these three disks to obtain the eclipse magnitude at each time step. The results of the two models agree to well within the expected light-curve measurement error. A preliminary model fit to the depths of five mutual eclipse events observed in 1985 and 1986 gives eclipse light-curve-derived estimates of the orbit radius C = 16.5 + 0.5 Pluto radii, the radius ratio B0 = 0.65 + 0.03, and the Charon:Pluto albedo ratio K — 0.55 + 0.15.
    [Show full text]
  • Solar and Lunar Eclipses Reading
    Eclipses What would you think if you were walking home from school on a sunny afternoon and the sun began to disappear? Would you be frightened? On rare occasions, the moon completely blocks the sun. The sky grows as dark as night even in the middle of a clear day. The air gets cool and the sky becomes an eerie color. If you don’t know what is happening, you can become very frightened. The moon doesn’t usually go directly between Earth and the sun or directly behind Earth. As the diagram below shows, the moon’s orbit around Earth is slightly tilted with respect to Earth’s orbit around the sun. As a result, in most months the moon revolves completely around Earth without the moon moving into Earth’s shadow or the moon’s shadow hitting Earth. When the moon’s shadow hits Earth or Earth’s shadow hits the moon, an eclipse occurs. An eclipse (ih klips) occurs when an object in space comes between the sun and a third object, and casts a shadow on that object. There are two types of eclipses: solar eclipses and lunar eclipses. (The words solar and lunar come from the Latin words for “sun” and “moon.”) The Tilt of the Moon’s Orbit The moon’s orbit is tilted with respect to Earth’s orbit. So the moon rarely goes directly between Earth and the sun. Solar Eclipses During a new moon, the moon is almost exactly between Earth and the sun. But most months, as you have seen, the moon travels a little above or below the sun in the sky.
    [Show full text]