How to observe an safely

SOLAR orthway eman N ctober by L 2014, e, O s Solar eclip Solar eclipses are quite rare and are often a major event. The SOLAR ECLIPSES passes right in front of the , blotting out its disc. Every time a 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 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 and is endorsed by the British Astronomical Association

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www.popastro.com www.britastro.org Designe When the Sun goes out solar eclipses would happen every . A solar eclipse occurs when the Moon However, as is often the case with science, comes between the Sun and the and things are a little more complex than casts a shadow on Earth. Anyone within a that, because the Moon’s around the certain area will see the Moon cross in front Earth is tilted compared with the Earth’s of the Sun. In a very narrow band across orbit around the Sun, and both are the Earth’s surface, the Moon passes squashed into an . So for an centrally in front of the Sun’s disc, eclipse to occur, the Moon has to be completely blotting it out for a “You’ll in the right place at the right time. remember it few minutes – this is a “total solar Because the Moon is smaller for the rest of eclipse”. Over a much wider area, than Earth, its shadow during an your life” the Sun is only partially covered eclipse covers only part of Earth’s by the Moon – a “partial eclipse”. It’s surface. So although there are always not as spectacular, but it’s a great thing to at least two solar eclipses a , from watch, and something you’ll remember for any one spot you usually see a solar eclipse the rest of your life! only every few , usually a partial Solar eclipses do not happen very often eclipse, though it may be total elsewhere. because the conditions are quite specific. See http://astro.ukho.gov.uk/eclipse for If the was in the same information on future eclipses. ● plane as Earth’s orbit around the Sun, total

total eclipse (umbra)

partial eclipse (penumbra)

Sun Moon Earth

How a solar eclipse works A solar eclipse occurs when the Moon comes between the Earth and the Sun and blocks out the light from the Sun. As the Earth and the Moon continue to move in relation to the Sun, the area of the total eclipse moves across the surface of the Earth. Thus the eclipse can be seen at different times from different parts of the world. N( ote that the diagram above is not to scale.)

What is a solar eclipse? a solar is What Did You Know? The last total solar eclipse visible from the UK was in 1999, when thousands of people flocked 1: to Cornwall to catch a glimpse. But for most of them it was cloudy. Just a few places saw the event through a break in the clouds. What is a solar eclipse? (cont.) Solar eclipse buzz words First contact The moment when the not a solid surface but is actually a layer Moon first starts to block the Sun and the about 500 km thick, which is very thin first small “bite” appears in the edge of the seeing as the Sun is 1,391,684 km across. Sun. The is completely covered during the total eclipse. Second contact The moment during a total eclipse when the Sun is completely Above the photosphere covered by the Moon. is a pink- layer of gas, about 2500 km thick, known as the chromosphere. Totality The period of time (usually a few During totality it is possible to see the minutes) in a total eclipse after second chromosphere in detail, as a ring around contact when the Sun is completely the darkness of the Moon’s silhouette. blocked by the Moon and a small part of the Earth is in full shadow. Baily’s Beads Because the edges of the Moon are not perfectly smooth, at the Partial phase The period of time when start and end of totality some only a section of the Sun is blocked by the shines through the valleys between Moon. In the UK none of us will see the mountains, with the appearance of beads. Sun completely covered, so the eclipse These are called Baily’s Beads after the will be partial throughout. scientist Francis Baily. Third contact The moment in a total Diamond Ring During a total eclipse, eclipse when the Sun reappears from if only one of Baily’s Beads is shining, a behind the Moon. Diamond Ring effect can be seen around Fourth contact The moment when the the lunar silhouette. Sun is completely uncovered again. Annular eclipse This occurs when the Photosphere The visible “surface” of Moon’s disc is smaller than the Sun’s, so the Sun. As the Sun is gaseous, this is the Sun is not fully covered.

When is the next eclipse? ● To find global circumstances and animations of the Earth for locations across the globe, visit http://astro.ukho.gov.uk/eclipse. ● To find the exact viewing conditions and watch an animation of what to expect a solar eclipse to look like where you live, visit http://www.timeanddate.com/eclipse/solar. 2: What you’ll see

diagrams on this page GENERATed using Skymap maybe prominences, which look flames like Sun’s outer atmosphere (the corona) and views gives of the amazing of Sun. This the eclipse, Moon the entirely blocks face the just beforeoccur totality. effect, Beads diamond the and which ring Observers may be able also toBaily’s see at second begins contact. total eclipse The of becomes Sun the covered by Moon. the when achieved. disc is is entire the This slowly second contact until Sun across the before you notice it. missing. 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Fourth the from when is the moving Moonends the and away starts ends.just totality as again, effect Beads diamond the and ring astronomical. our own atmosphere anything rather than limb, caused which is by in turbulence probably at a lot see the of shimmering Sun. But the against silhouetted you’ll or valleys mountains see onlimb the can that it isn’t completely smooth, you as limb) the as (known you and might see than the . could notice Moon’s that the darker is disc Moon’s the if happens to one disc cross you birds may stop singing. stop may birds itand feel colder, can go quiet and animals temperature the change totality can During another. than one direction in sharper have that they will oddsee an shape, being eclipse,particularly at you maximum may when you look at shadows landscape, the in not notice a huge difference. But it’s if clear, skythe goes dark. it If cloudy, is you might totality, edgearound the of Sun. During the Third contact when is Third total eclipse the Observers may be able toBaily’s see lookAlso at edge the of Moon the If youIf have a projecting are and black, they are still part of the Sun and black, of and part Sun the still they are the imagethe (see 3), section or are 9:45 output. Although look oon moved from right to across left viewing itviewing solar a safe filter, using a.m. magnetic field restricts its light light its restricts field magnetic you may notice that are there These are places are These where Sun’s the dark spots Sun:on sunspots. the 10:00 a.m. 10:15 a.m. 10:40 a.m. ● 3: View using household items completely covered completely briefthe period of when totality is Sun the your eyes. is only The exception rule to this not providewill adequate protection for no matter what anyone says, circumstances – look directly at the Sun! And caution. You should never, – under any ever hazardous and should only be attempted with your eyes! How NOT to view a solar eclipse: with Danger! intense visibleintense light damage that can the because Sun’s the photosphere emits very such as bin liner or gift wrap. or gift liner such bin as Even though cut down Sun’s the light by 100,000 times. they have dark to them special material in youglasses to get used at cinema, but the undamaged filters use.safe are to damage such holes as or scratches, only as hold of a viewer, you should it check for to eclipse viewthe it. you If manage to get youmaterial and inlaid, hold up them to viewers made are of special with card directly.view eclipse the Eclipse enjoyable and safe way to or shades a that is then ofpair viewers eclipse youIf able are a to find viewers Eclipse paper! many images of on eclipse one the piece of paperthe watch and you as safely observe Hold colander the and Sun the between a piece and hand of paper other. the in hold and to Sun the colander the one in kitchen: a colander. Standyour with back item an tois use you the in normally find By simplest the far way to eclipse view an Colanders Viewing an eclipse is dangerous dangerous is eclipse an Viewing Never material that use just looks dark, Eclipse shades a bit are 3D the like card Viewing a solar eclipse is potentially . eclipse shades,eclipse 4. section see before you look at Sun! the viewerthe – put viewer the to your eyes your eyes. you do could damage permanent still to cut out light, dangerous the so infrared it cuts down visible the light, it might not to use, suggested as below. hold of easily – or even safe – that are make of equipment.access types to these directly, Sun the but most of do us not have solar telescopes special use or filters view to ormethod. any Astronomers other direct a telescopeat binoculars, through Sun the become permanently damaged. for Sun the a few seconds for your eyes to proper protection. 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Nigel Evans/ View using household Pinhole viewers items (cont.) pinhole small of Sun to Sun to Sun

the cards should be at least 1 m apart: the further apart, the larger the image of the Sun cereal packet A simple yet safe way to view the solar piece of card, allowing the eclipse to be eclipse is by making a pinhole viewer. viewed safely. Pinholes allow light through them, An alternative to this is to use a and can create an image like a . All cereal box or similar. Make a pinhole you need for this are two pieces of white in one edge. Point this towards the Sun card. Poke a small hole in one piece of card and you’ll see a tiny image of the Sun using a compass or a similar tool. Stand projected on to the inside of the packet. with your back to the Sun. Hold both Put white paper or card on the inside to cards up, with the one with the pinhole make it easier to see. closer to the Sun. The light through the Never look through the pinhole at the Sun, pinhole can be projected on to the other but only at the projected image.

Mirrors A small , such as a make-up mirror, can be used to reflect the image of the covered mirror eclipse onto a white wall. Do not use with gap ~3–5mm a magnifying mirror. Do not look into the mirror at the eclipse as this is just as dangerous as looking directly at the Sun. Cover the mirror with paper in which you have made a hole no more than window 5 mm across. Stand with your back to the eclipse image on screen eclipse. Use the mirror to reflect an image or wall in dark room of the Sun onto a light-coloured wall, being careful not to reflect the sunlight and mirror size should make the image into anyone’s eyes. brighter. To make the image clearer to see, This works well when you are about use an indoor wall in a house and reflect 5 m away from the wall. The smaller the image in through a window. the mirror and the further away the Notice that the shape of the hole – even wall, the sharper the image you should a triangle – still gives a circular disc of the get. Experimenting with the distances Sun.

Did You Know? There was an annular eclipse visible from the north of Scotland in 2003. On that occasion, early morning mist spoiled the view for many. View using household Projection using binoculars or a telescope items (cont.) ell/Galaxy g obin Sca R obin A pair of binoculars can stand in for a Sun drifts out of the , it might pinhole. Cover one with the lens melt the inside of the eyepiece! So take cap, then when the binoculars are pointed great care, or use an old eyepiece (many at the Sun you should see its image older used metal rather than projected onto the plain card. Use the plastic). focus wheel to sharpen the image. This An alternative is to completely cover method works best if both the card and the top end of the telescope with suitable binoculars are mounted on a tripod. solar film, such as Baader AstroSolar. Never, ever, look directly into the binoculars This is available in A4 sheets which you while they are pointed at the Sun. can cut to fit. As long as the material fully You can use a telescope in the same covers the top end, with no chance of the way. If it has an (lens or mirror filter being dislodged and no chinks in size) larger than about 50 mm, it may come the holder, it is perfectly safe to view the with a cap that reduces its aperture to this partial eclipse through the telescope. size for safety. But while this method is This is also the material to use if you safe for humans, unless you are careful it want to photograph the eclipse through can damage your valuable binoculars or a telephoto lens. An alternative is to telescope. This is because the Sun’s light photograph the projected view with an is focused on the inside of the eyepiece, ordinary camera or even your phone which could contain plastic parts. If the camera.

Did You Know? An eclipse of the Moon occurs when the Moon passes through the shadow of the Earth. Unlike a solar eclipse, this only happens at night, and it can be seen from anywhere on Earth where the Moon is visible. 4: Resources and websites ● ● ● ● ● ● ● ● ● ● resourcesPrimary Resources for teachers ● ● Buy safe eclipse viewers or projectors in the UK ● Make an eclipse viewer ● general in Eclipses www.astromediashop.co.uk/ Eclipses explained Eclipses www.amazon.co.uk/ Write article newspaper a UK UK Hydrographic Office Paper model of a solar eclipse a solar of Paper model How to make a shoe-box viewer to safely viewer How to make to safely ashoe-box your Construct own viewer eclipse your town select Calculator: Eclipse

www.harrisontelescopes.co.uk/acatalog/ www.eclipseglasses.co.uk in Francisco, San The Exploratorium USA, Society Royal Astronomical corr&keywords=rainbow+symphony+ s=aps&ie=UTF8&qid=1418390762&sr=1-1-cat Shades- newspaper-article for-schools-and-teachers/2555-solar-eclipse- www.ras.org.uk/education-and-careers/ explained www.solareclipse2015.org.uk/solar-eclipses- astro.ukho.gov.uk/eclipse www.youtube.com/watch?v=Sl eclipse solar view the M sunearthday..gov/2008eclipse/materials/ www.timeanddate.com/eclipse role-play for-schools-and-teachers/2554-solar-eclipse- www.ras.org.uk/education-and-careers/ a solar eclipse Role-play Solar_ jsp?id=2265 www.scholastic.com/browse/subarticle. www.exploratorium.edu/eclipse/how.html gives ways simple Sun viewing of the everyone/2558-solar-eclipses www.ras.org.uk/education-and-careers/for- y_solar_eclipse.pdf E clipse_Glasses.html B lack/dp/ B 00

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● ● ● ● ● ● ● ● resources Secondary ● ● ● www.firstlightoptics.com/solar-filters/baader- www.britastro.org/solarviewers www.widescreen-centre.co.uk/ www.telescopehouse.com/acatalog/ The maths of a solar eclipse (year aeclipse solar The of maths 10–11) HM Nautical Almanac Office: solar and Almanacsolar Nautical and HM Office: general eclipse Space European Agency: Solar eclipse worksheet (years worksheet 7–9) eclipse Solar historical and Williams: topical Sheridan A step-by-step guide to making a a guideto making A step-by-step European Space European Resource Education solar-eclipse-observing-glasses.html THE Viewing_ solar-eclipse-year-10-11 schools-and-teachers/2557-the-maths-of-a- www.ras.org.uk/education-and-careers/for- lunar eclipses lunar www.esa.int/ information www.eclipse.org.uk worksheet-years-7-9 for-schools-and-teachers/2556-solar-eclipse- www.ras.org.uk/education-and-careers/ W www.clock-tower.com/eclipse.htm eclipse information eclipse eclipse_viewer.htm hilaroad.com/camp/projects/eclipse_viewer/ boxcereal viewer Office links to eclipse viewing information eclipse to links Office www.esero.org.uk/news/solar-eclipse-2012 hat_is_an_eclipse OLAR _S P ack.html _ O

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Resources and websites Keep in touch (cont.) ● Follow @RAS_outreach on Twitter and tweet to tell us when and where you’ll be viewing an eclipse. Send us your photos!

● Schools can request eclipse-related resources or electronic discussions with our Education, Outreach and Diversity Officer. Email [email protected] if you are interested.

Watch Lucie Green explain safe viewing The SPA has produced a video starring Lucie Green of BBC TV’s Sky at Night, in which she shows how to observe an eclipse safely. To view it, visit www.popastro. com/news/newsdetail.php?id_ nw=329 ER ALEXAN D MAX