Measures of Central Tendency: Mean, Median and Mode
Aurora- The Natural Light Display in the Sky
1. An aurora (plural aurorae orauroras; fromthe Latin wordaurora, "dawn") isa natural lightdisplayinthe
sky,particularlyinthe high-latitude(ArcticandAntarctic) regions.Thislightdisplayiscausedbythe
collisionof atomswithenergeticchargedparticlesinthe high-altitude atmosphere (thermosphere).The
chargedparticlesoriginate inthe magnetosphereandsolarwindand,onEarth, are directedbythe
Earth's magneticfieldintothe atmosphere.
An aurora isclassifiedaseitheradiffuse ora discrete aurora.A diffuse auroraisa featurelessglowinthe
skythat may not be visible tothe nakedeye evenonadarknightand definesthe extentof the auroral
zone (the areain whichaurorasare visible).Discreteaurorasare sharplydefinedfeatureswithinthe
diffuse aurorathatvary inbrightnessfromjustbarelyvisible tobrightenoughbywhichtoreada
newspaperatnight.
In northernlatitudes,the effectisknownasthe aurora borealis(orthe northernlights),namedbyPierre
Gassendi in1621 afterthe Roman goddessof dawn,Aurora,andthe Greekname for the north wind,
Boreas.The northernlightshave hada numberof namesthroughouthistory.The Cree call the
phenomenonthe "Dance of the Spirits."InEurope in the Middle Ages,the auroraswere commonly
believed tobe a signfromGod. Aurorasseennearthe magneticpole maybe highoverhead,butfrom
fartheraway,theyilluminatethe northernhorizonasagreenishglow orsometimesafaintred,as if the
sunwere risingfroman unusual direction.Discrete auroras oftendisplaymagneticfieldlinesorcurtain-
like structures.Theycanchange withinsecondsorglow unchangingforhours,mostofteninfluorescent
green.The aurora borealismostoftenoccursnearthe equinoctes.
Its southerncounterpart,the aurora australis(orthe southernlights),hasalmostidenticalfeaturesto
the aurora borealis.Itchangessimultaneouslywiththe northernauroral zone andisvisible fromhigh
southernlatitudesinAntarctica,SouthAmerica,New Zealand,andAustralia.
Aurora Australis
2. Aurora is just visible at the south pole, so it is sometimes called the southern light. Aurora is seen
in a very high, but the hila viewed from a distance it will look like being on the horizon.
Light at the Aurora Australis is usually colored green, sometimes reddish or red faded as if the
sun was rising. In the glow ersebut, sometimes it appears the lines of the magnetic field of light,
almost like a curtain of light terrlihat beautiful giant.
This beautiful aurora can be seen from several places, especially the southern part of the earth.
The areas that can enjoy this Aurora is Antarctica, South America, New Zealand, Australia.
Aurora ini hanya terlihat di kutub selatan, sehingga sering pula disebut cahaya selatan. Aurora ini
terlihat di tempat yang sangat tinggi, namun hila dilihat dari kejauhan akan tampak seperti
berada di garis cakrawala.
Cahaya di Aurora Australis ini biasanya berwana hijau, terkadang kemerahan atau merah pudar
seolah-olah matahari sedang terbit. Pada pendaran cahaya ersebut, terkadang tampak adanya
garis-garis cahaya medan magnet, nyaris terrlihat seperti tirai cahaya raksasa yang indah.
Aurora yang indah ini bisa dilihat dari beberapa tempat, khususnya bagian selatan bumi.
Wilayah-wilayah yang bisa menikmati Aurora ini adalah Antartika, Amerika Selatan, New
Zealand, Australia.
Aurora Borealis
Aurora ini juga sering disebut cahaya utara. Nama Borealis sendiri berasal dari Boreas yang
merupakan bahasa Yunani untuk angin utara. secara keseluruhan, hampir tidak ada bedanya
dengan Aurora Australis. Perbedaan hanya terletak pada lokasi terjadinya Aurora.
Aurora isalsooftencalledthe NorthernLights.The name itselfcomesfromBoreasBorealiswhichisthe
Greekwordfor the north wind. Overall,almostnodifferencewiththe AuroraAustralis.The only
difference liesinthe locationof the Aurora.
. Aurora Borealis
Borealis adalah kata Yunani untuk angin utara. Pada bagian belahan bumi utara,gejala alam yang sama ini disebut
sebagai Northern Lights atau aurora borealis.Aurora Northern Lights hanya dapatdilihatpada wilayah Lingkaran
Arktik, di sebelah utara Kanada,Alaska,Rusia,dan Skandinavia.
Pada belahan bumi bagian bumu utara,Aurora Baroealis terjadi seringkali terlihatdengan warna kemerahan di ufuk
utara. Seolah-olah menunjukkan matahari akan terbitdari bagian itu. Aurora Borealis kerap kali terjadi pada waktu
tertentu pada bulan September dan Oktober, kemudian antara bulan Maretdan April
3. Borealisisthe Greekwordfor the northwind.Inthe northernhemisphere,the same natural
phenomenonisreferredtoasthe NorthernLights,oraurora borealis.AuroraNorthernLightscanonly
be seeninthe regionof the ArcticCircle,innorthernCanada,Alaska,Russia,andScandinavia.
In the northernhemisphere bumu,AuroraBaroealishappenoftenseenwithrednessonthe northern
horizon.Asif showingthe sunwill rise fromthe passage.AuroraBorealisoftenoccurat specifictimesin
SeptemberandOctober,andbetweenMarchand April