{"id":11683,"date":"2011-07-16T09:44:26","date_gmt":"2011-07-16T09:44:26","guid":{"rendered":"http:\/\/www.bitacoradegalileo.com\/en\/?p=11683"},"modified":"2011-07-17T14:19:58","modified_gmt":"2011-07-17T14:19:58","slug":"the-lunar-terminator","status":"publish","type":"post","link":"http:\/\/www.bitacoradegalileo.com\/en\/2011\/07\/16\/the-lunar-terminator\/","title":{"rendered":"THE LUNAR TERMINATOR"},"content":{"rendered":"

Today we write an explanation of the meaning of “lunar terminator”. I searched the internet and not fully satisfied me anything I found. So I accepted the challenge to explain it myself, with some graphic support, to help understand it better.<\/p>\n

It is well known\u00a0that\u00a0the moon,\u00a0the\u00a0beautiful heavenly body that serves us as\u00a0companion\u00a0day and night, though many think\u00a0it is only\u00a0at night,\u00a0as\u00a0I say that\u00a0everyone knows\u00a0has\u00a0phases.\u00a0This means that\u00a0the surface that\u00a0shows illuminated by\u00a0the Sun,\u00a0because that\u00a0is the source of its brilliance,\u00a0is changing every\u00a0day,\u00a0even\u00a0every moment, showing almost always (except\u00a0full moon)\u00a0one portion\u00a0illuminated and another dark\u00a0separated by\u00a0a line that\u00a0marks the division\u00a0between selenite\u00a0day\u00a0and night: The\u00a0lunar terminator<\/strong>.\u00a0This line,\u00a0of course, is constantly changing\u00a0its location, and it is where\u00a0the sunlight\u00a0is flush\u00a0and\u00a0an observer on\u00a0the moon’s surface\u00a0at that point\u00a0would see the sun\u00a0on\u00a0the horizon.\u00a0The terminator\u00a0has two ends, north and south, called\u00a0cusps.<\/p>\n

It\u00a0\"\"<\/a><\/em>is important to notice,\u00a0and it\u00a0can be seen in the photograph,\u00a0how\u00a0it is along\u00a0the terminator where we\u00a0can see the shadows\u00a0reveal the\u00a0depth of the\u00a0crater walls\u00a0and\u00a0the height of the mountain ranges.\u00a0Looking at the\u00a0Northern Hemisphere, we see\u00a0a crater, just above the\u00a0terminator, which is the\u00a0large crater\u00a0Plato<\/strong>\u00a0(101 km\u00a0in diameter and\u00a0walls\u00a02400 meters high) below\u00a0Archimedes<\/strong>\u00a0(55 km\u00a0and 1850\u00a0m), almost\u00a0in darkness\u00a0and then\u00a0a mountain range,\u00a0almost\u00a0straight, near the\u00a0landing site of\u00a0Apollo\u00a0XV, which is called Montes\u00a0Apenninus<\/strong>, in memory of\u00a0its namesake\u00a0mountain range\u00a0in Italy.\u00a0This\u00a0ends,\u00a0at its western end, in the crater\u00a0Eratosthenes\u00a0<\/strong>(60 km\u00a0and 3150\u00a0m), a resident\u00a0of the great Copernicus\u00a0(90 km\u00a0and 3900\u00a0m),\u00a0“The Lord of\u00a0the Moon” with its\u00a0radial system\u00a0of ejecta at the time\u00a0impact.\u00a0Well, we see\u00a0how\u00a0Copernicus\u00a0<\/strong>receives sunlight more\u00a0perpendicular\u00a0than the other\u00a0craters\u00a0near the\u00a0terminator,\u00a0and we cannot appreciate\u00a0it’s depth,\u00a0though\u00a0it exceeds\u00a0the highest point in\u00a0Spain, Mount\u00a0Teide\u00a0in\u00a0Tenerife\u00a0(3718\u00a0m above\u00a0sea level).<\/p>\n

The rest\u00a0of the illuminated\u00a0surface on the moon, further from\u00a0our line, it\u00a0seems to us\u00a0almost\u00a0flat, without being, because of the effect\u00a0described\u00a0in\u00a0the perpendicularity of the\u00a0sun\u00a0and the absence\u00a0of shadows.<\/p>\n

It is easily understood that\u00a0when the moon\u00a0is fully illuminated (the\u00a0full moon\u00a0phase), there is no\u00a0terminator,\u00a0and we can not\u00a0take advantage of\u00a0this inclination\u00a0of the sun\u00a0for\u00a0optimal observation.\u00a0That’s why astronomers, against\u00a0the belief\u00a0of the majority,\u00a0avoid this stage that only\u00a0poses problems to the observer.\u00a0When studying deep-sky objects, the full moon works as a huge\u00a0spotlight installed\u00a0in the sky that\u00a0dazzles and prevents the vision of\u00a0lower luminosity\u00a0objects\u00a0such as\u00a0star clusters, nebulae\u00a0and\u00a0distant galaxies.\u00a0If\u00a0we want to\u00a0study the moon,\u00a0the perpendicularity of the\u00a0rays also\u00a0greatly complicates\u00a0the study, revealing\u00a0even\u00a0necessary to use\u00a0a\u00a0moon filter\u00a0(a\u00a0light green\u00a0or yellow\u00a0would be appropriate) to avoid\u00a0damage\u00a0to our eyes\u00a0producing a\u00a0prolonged observation\u00a0(The reflecting\u00a0light of the\u00a0full moon is\u00a012 times\u00a0higher than it radiates at waxing or waning crescent).<\/p>\n

I know\u00a0amateurs who\u00a0keep their\u00a0astronomical\u00a0equipment in such\u00a0situations and\u00a0use them again\u00a0only\u00a0when the moon\u00a0decreases the intensity\u00a0of its brightness.\u00a0Definitely,\u00a0these guys\u00a0aren’t werewolves nor\u00a0are in love,\u00a0because\u00a0they really do appreciate\u00a0the\u00a0full moon.<\/p>\n

A couple of\u00a0definitions\u00a0alien to me:<\/p>\n

WIKIPEDIA<\/strong>: The Lunar terminator<\/strong> is the division between the illuminated and dark parts of the Earth’s Moon.<\/p>\n

Elcielodelmes.com<\/strong>:\u00a0The\u00a0area bordering\u00a0the light\u00a0and shadow\u00a0is called the\u00a0terminator.<\/p>\n

One last example\u00a0to end:
\n\"\"<\/a>
\nSouth\u00a0Moon\u00a0photography,\u00a0one\u00a0of the most\u00a0rugged.\u00a0Being close to\u00a0the terminator,\u00a0the craters\u00a0can be seen\u00a0in all its splendor.<\/em><\/p>\n

 <\/p>\n

Anyway,\u00a0that’s all.\u00a0I did not want\u00a0to do\u00a0a superficial, long\u00a0and tedious outline with excessive technical details,\u00a0less interesting, nor\u00a0a walk too shallow\u00a0not to allow\u00a0to understand the meaning\u00a0and importance of the\u00a0lunar terminator, that\u00a0ally\u00a0helping us\u00a0in contemplation, study and\u00a0enjoy of our beautiful\u00a0satellite.\u00a0I hope this\u00a0small contribution\u00a0is helpful.<\/p>\n

May you have clear skies\u00a0and happy\u00a0observations.<\/p>\n","protected":false},"excerpt":{"rendered":"

Today we write an explanation of the meaning of “lunar terminator”. I searched the internet and not fully satisfied me anything I found. So I accepted the challenge to explain it myself, with some graphic support, to help understand it better. It is well known\u00a0that\u00a0the moon,\u00a0the\u00a0beautiful heavenly body that serves us as\u00a0companion\u00a0day and night, though […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[33],"class_list":["post-11683","post","type-post","status-publish","format-standard","hentry","category-moon","tag-moon"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/posts\/11683","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/comments?post=11683"}],"version-history":[{"count":10,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/posts\/11683\/revisions"}],"predecessor-version":[{"id":11691,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/posts\/11683\/revisions\/11691"}],"wp:attachment":[{"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/media?parent=11683"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/categories?post=11683"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.bitacoradegalileo.com\/en\/wp-json\/wp\/v2\/tags?post=11683"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}