Astronomy - September 2015

UMBRA

Penumbral

eclipse begins

8:12 P.M. EDT

Partial eclipse begins

9:07 P.M. EDT

Totality begins

10:11 P.M. EDT

Greatest eclipse

10:47 P.M. EDT

Totality ends

11:23 P.M. EDT

Partial eclipse ends

12:27 A.M. EDT

Penumbral

eclipse ends

1:22 A.M. EDT

N

E

PENUMBRA

WWW.ASTRONOMY.COM 57

This year, on the evening of Sunday, September 27, throughout
North and South America, Europe, and Africa, people under a
clear sky will witness a celestial event that will excite the media
and engage the public. A total lunar eclipse will present its eerie
glow during a perfect alignment of the Sun, Earth, and the Moon.
Coincidentally, this also will be the night that the Super Moon, the
Harvest Moon, and the last in a series of four eclipses that astrono-
mers call a tetrad are on display.
These last three “events” may not be significant to astronomers,
but they do prove so monumental to various forms of media that
this night will surely become the foremost sky event of the year.

Subsequently, this is our call to action: This Super Moon/Harvest

Moon/tetrad total lunar eclipse will present us with a rare oppor-

tunity to share our acute expertise and passion for astronomy with

a wider audience. Let’s get ready!

Can you tell the difference?

The public phenomenon called the Super Moon began in 2011

when online and mainstream media picked up on the obscure

tidbit of knowledge that the Full Moon’s distance from Earth var-

ies. Many of my colleagues and I became instantly skeptical of

this newfound interest in something astronomers refer to rarely (if

ever) as a “perigee syzygy” — perigee meaning “closest to Earth”

and syzygy meaning “a lineup of three celestial bodies.”

Like all researchers, astronomers are naturally wary of the

media when it comes to reporting so-called scientific stories. We

have seen so many articles that overblow and embellish small dis-

coveries, completely ignore large ones, garble the facts, or utterly

miss the point. On the surface, the Super Moon seemed like yet

another overhyped tale that would confuse

and anger the public when they

observed a Moon no larger than the

one from their memories. But I

was wrong. The media can han-

dle a Super Moon, and the

public simply loves it.

An observer using just his

or her eye can’t differentiate

the Moon’s apparent size

from night to night. However,

when one compares a Super

Moon to the farthest Full

Moon, a so-called “Puny Moon,”

the variance is dramatic. The

Super Moon is more than 31,000

miles (50,000 kilometers) closer

and consequently has a 14 per-

cent larger diameter with a 30

percent larger surface area than

On September 27,

the biggest Full

Moon of the year

will pass through

Earth’s shadow.

by Dean Regas

The September 27 total eclipse of the Super Moon lasts a total of 5 hours

and 10 minutes. The entire event will be visible from clear locations east of

the Mississippi River and throughout South America and western Europe.

More westerly locations in the U.S. will see progressively less of the eclipse.

This image of the penumbral

lunar eclipse on October 18, 2013,

shows what the early stages of the

September 27 event will look like.

CHUCK MANGES

ASTRONOMY

: ROEN KELLY, AFTER FRED ESPENAK/NASA