Supermoon Why its the best lunar show in the solar system

Supermoon peaked Sunday morning but good viewing will continue for the next few days. The unusual relationship between Earth and the moon makes supermoon a particularly good show.

By Mark Sappenfield Staff writer / June 23 2013

Supermoon rises behind the Home Place clock tower in Prattville Ala. Saturday.

Dave Martin/AP

Enlarge

Supermoon officially arrived at about 7 a.m. Eastern Daylight Time Sunday morning with the moon making its closest swing by Earth this year. About a half hour later the moon reached full status making it appear 12 percent larger and 30 percent brighter than a regular full moon.

Skip to next paragraph In Pictures Space photos of the day The Moon Are you scientifically literate Take our quiz

Supermoon Will it be 5 times larger Not exactly. Still cue 'Moonstruck.' Moon hit by boulder size meteoroid causing 'explosion' visible from Earth ( video) ' else if (google_ads.length 1) ad_unit '' document.getElementById( ad_unit ).innerHTML ad_unit google_adnum google_ads.length return var google_adnum 0 google_ad_client pub 6743622525202572 google_ad_output 'js' google_max_num_ads '1' google_feedback on google_ad_type text // google_adtest on google_image_size '230x105' google_skip '0' //

Subscribe Today to the Monitor

Click Here for your FREE 30 DAYS ofThe Christian Science MonitorWeekly Digital Edition

Don't worry if you missed it. The effect should still linger for a few nights meaning Sunday Monday and even Tuesday should give a good sense of this year's supermoon.

And social media was alight with the event with pictures of Saturday night's supermoon making an appearance from Facebook to Instagram.

RECOMMENDED Are you scientifically literate Take our quiz

The show is the product of a cosmic quirk. Since planets and moons orbit in ellipses not circles there are times when they are closer to what they're orbiting and times when they're farther away. For moons the point when they're closest to their planet is called perigee the point farthest away is called apogee.

For Earth and the moon perigee and apogee happen once each month since the moon orbits the Earth once every 27 days. But because of small inconsistencies in the orbits the moon's closest approach and its farthest distance are always slightly different.

The moon hit its monthly perigee Sunday morning but what makes it worthy of the name supermoon was that it was the closest perigee of 2013. Moreover since it coincided almost perfectly with a full moon the effect was enhanced.

The moon's farthest apogee this year has already happened and is set to repeat itself next year during the Jan. 15 2014 full moon. To see the visual difference in size between a perigee and apogee moon click here.

But what makes the moon so special If everything in the solar system orbits in an ellipsis shouldn't we have a supersun too.

In fact we do. Since we orbit the sun once a year supersuns only happen once a year. Our closest swing to the sun called perihelion also already happened this year and will happen again on Jan. 4 2014. (An un supersun when the sun seems smallest at aphelion is just around the corner July 5.)

But will there be this much buzz next January with sungazers filling Twitter with pictures of a gigantic sun Don't count on it.

The reason the sun is obviously much farther away from Earth than is the moon so the effect is not so noticeable. For Earth the distance between aphelion and perihelion is about 3 million miles. But even at perihelion the Earth is still 91 million miles from the sun.

In addition Earth's orbit around the sun is more nearly circular than is the moon's orbit around us with only Venus and Neptune having more circular orbits than Earth. Mercury has the most eccentric orbit ranging from a perihelion of 29 million miles to an aphelion of 43 million miles meaning it has a truly dramatic supersun (if you can stand the 800 degree Fahrenheit temperatures on the sun side surface).

By contrast the moon's orbit around Earth is the most elliptical orbit of any major moon in the solar system. Combine that with the fact that the moon is comparatively close to Earth so it looks large in our skies and supermoon earns its name.

RECOMMENDED Are you scientifically literate Take our quiz

Articles Source here