{"id":1380,"date":"2014-01-12T00:00:35","date_gmt":"2014-01-12T00:00:35","guid":{"rendered":"http:\/\/www.skycaramba.com\/blog\/?p=1380"},"modified":"2014-01-05T03:34:16","modified_gmt":"2014-01-05T03:34:16","slug":"farthest-full-moon-of-the-year","status":"publish","type":"post","link":"https:\/\/www.skycaramba.com\/blog\/2014\/01\/12\/farthest-full-moon-of-the-year\/","title":{"rendered":"Farthest full moon of the year"},"content":{"rendered":"

\u00a1SkyCaramba! Weekly astronomy blog for the week ending January 18, 2014<\/em><\/p>\n

The moon will be at apogee on January 16. That\u2019s the farthest it will be from the earth during its orbit. It will be full that day too. The two things won\u2019t happen on the same date again until March 2015. In other words, all the full moons later this year and early next year will be closer to us than the one this month. Why aren\u2019t they all the same distance?<\/p>\n

The average time between full moons is a little more than 29 days, 12 hours. As the moon goes around the earth, it takes that long for the moon to line up in nearly the same way with the sun and earth. But going from apogee to apogee takes only about 27 days, 8 hours. So from month to month for the next 14 months, apogee will get earlier and earlier compared to the full moon until it\u2019s an entire lunar month ahead and is actually happening with a full moon again.<\/p>\n

This happens because while the moon goes around the earth, the earth goes around the sun. One lunar orbit takes about 27 days, 8 hours. During that time, the earth has moved. By the time the moon gets back to where it was at the start of its orbit, it\u2019s at a different angle from the sun. It takes two more days to catch up to the lineup that makes it full.<\/p>\n

The shorter period is called the sidereal period. It\u2019s measured by how long it takes for an orbiting object to be against the same background of distant stars. The longer period is called the synodic period. It\u2019s measured by how long it takes for an orbiting object to return to the same place compared to the sun.<\/p>\n

\"\"<\/a><\/p>\n

It\u2019s easy to observe the synodic period by just looking at the moon\u2019s phase. You can count the days yourself between full moons, or first quarter moons, etc. It\u2019s probably marked on a calendar in your home.<\/p>\n

It\u2019s almost just as easy to observe the moon\u2019s sidereal phase. You just need to pay attention to which constellation the moon is in or close to at a given time. This month\u2019s full moon is in Cancer between Gemini and Leo. February\u2019s will be at the feet of Leo. March\u2019s will be between Leo and Virgo.<\/p>\n

Over the course of a month, you can also observe how far north or south the moon is. Make a note of when the moon is farthest north or south and count the days until it\u2019s that far north or south again. It\u2019ll take about 27 days. It should be obvious now, eventually there will be a full moon that is farthest north for the entire year and it will take about 14 months for the full moon to be that far north again.<\/p>\n

This is a fun thing to observe. But there\u2019s even more to the story. The moon\u2019s distance is not tightly aligned with how far north or south of the equator it is. This month\u2019s apogee is three days after northern lunistice (the moon\u2019s position farthest north before it starts going south again). That\u2019ll happen again in about ten years. This drift happens because of the gravitational tug between the earth and moon. I\u2019ll go into that another time.<\/p>\n

\u00a1SkyCaramba!<\/p>\n","protected":false},"excerpt":{"rendered":"

This month’s full moon is the farthest one from us all year long. Why isn’t every full moon the same distance away? I’ll tell you.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[276,59,142,459,91],"_links":{"self":[{"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/posts\/1380"}],"collection":[{"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/comments?post=1380"}],"version-history":[{"count":4,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/posts\/1380\/revisions"}],"predecessor-version":[{"id":1385,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/posts\/1380\/revisions\/1385"}],"wp:attachment":[{"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/media?parent=1380"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/categories?post=1380"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.skycaramba.com\/blog\/wp-json\/wp\/v2\/tags?post=1380"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}