First Total Lunar Eclipse of 2015 Occurs as Blood Moon on Holy Saturday, April 4

Summary: The first total lunar eclipse of 2015 appears Holy Saturday, April 4, as a blood moon.

visibility of total lunar eclipse of April 4, 2015: Fred Espenak/NASA/GSFC, CC BY 2.0, via NASA Eclipse Web Site

The first total lunar eclipse of 2015 appears on the first Saturday in April as the third of a quartet of total lunar eclipses occurring at intervals of approximately six months over a span of 17 months.

In astronomy, the phenomenon of four closely spaced total lunar eclipses, separated successively by about six months, is termed as a tetrad (Ancient Greek: τέσσαρες, téssares, "four"). The total lunar eclipse Tuesday, April 15, 2014, initiated the tetrad. The second in the series occurred Wednesday, Oct. 8, 2014. The fourth occurrence will close the tetrad of 2014-2015 on Monday, Sept. 28, 2015. A popular name for the moons in a lunar tetrad is blood moon.

A total lunar eclipse (Ancient Greek: ἐκ, ek, “out” + λείπω, leípō, “I leave behind”) occurs during the full moon phase of the eight phase monthly lunar cycle. During its full phase, the moon is in syzygy (Ancient Greek: σύζυγος, suzugos, “yoked together”), or alignment, with the sun and the Earth. Positioned in the middle in the solar-lunar sandwich, the Earth casts its shadow upon the moon, thereby eclipsing, or obscuring, the lunar surface.

The show demurely begins Holy Saturday, April 4, at 2:01 a.m. Pacific Daylight Time (5:01 a.m. Eastern Daylight Time; 09:01 Greenwich Mean Time).

The moon encounters the penumbra (Latin: paene, "almost" + umbra, "shadow"), the faint, outer region of Earth's shadow. Apparent within 55 minutes, the penumbral effect imparts a smudginess to the moon's left rim.

Drama vividly commences at 3:16 a.m. PDT (6:16 a.m. EDT; 10:16 GMT), with the moon's passage behind the Earth into the terrestrial umbra (Latin: umbra, "shade, shadow"), or amber-colored shadow. The umbra travels across the lunar disk for 103 minutes (1 hour 43 minutes). At 4:58 a.m. PDT (7:58 a.m. EDT; 11:58 GMT), the umbra completely obscures the moon, as viewed by Earthlings.

Depending upon location, the eclipse is viewable in totality or in partiality. The interruption of the eclipse by sunrise creates a partial eclipse for U.S. locations east of the Mississippi River. Totality, or the total eclipsing of the moon within the earthly shadow, is available for eastern Asia, Oceania, western Canada, mostly Mexico, and U.S. locations west of the mighty Mississippi.

The National Aeronautics and Space Administration (NASA) is providing a live viewing of the first total lunar eclipse of 2015 via Marshall Space Flight Center's Ustream channel.

The live webcast, which starts at 6 a.m. EDT (3 a.m. PDT; 10 GMT), is available at: http://www.ustream.tv/channel/nasa-msfc

This first total lunar eclipse of 2015 stands out as the shortest in duration of totality for the 21st century. Totality only lasts for 4 minutes 43 seconds (283 seconds) because the moon is passing on the periphery, or outskirts, of Earth's sunlight-induced shadow.

Although brief, spring 2015's total lunar eclipse is nonetheless stunningly ablaze as a blood moon. On the other side of the Earth, the sun's light inflames the terrestrial rim so that all the Earth's sunrises and sunsets, through refraction, or bending, bathe the Earth's coverage of the moon with a blood red shadow.

lunar path behind Earth during total lunar eclipse of April 4, 2015: Fred Espenak/NASA/GSFC, CC BY 2.0, via NASA Eclipse Web Site

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

visibility of total lunar eclipse of April 4, 2015: Fred Espenak/NASA/GSFC, CC BY 2.0, via NASA Eclipse Web Site @ http://eclipse.gsfc.nasa.gov/eclipse.html

lunar path behind Earth during total lunar eclipse of April 4, 2015: Fred Espenak/NASA/GSFC, CC BY 2.0, via NASA Eclipse Web Site @ http://eclipse.gsfc.nasa.gov/eclipse.html

For further information:

Phillips, Dr. Tony. “Total Eclipse of the Moon.” NASA Science News > Science@NASA Headline News > 2015. March 30, 2015.
Available @ http://science.nasa.gov/science-news/science-at-nasa/2015/30mar_lunareclipse

Rao, Joe. "Total Lunar Eclipse Saturday: How to See the Blood Moon." Space.com. April 3, 2015.
Available @ http://www.space.com/29008-total-lunar-eclipse-saturday-visibility.html

ScienceAtNASA. "ScienceCasts: Total Eclipse of the Moon." YouTube. March 30, 2015.
Available @ https://www.youtube.com/watch?v=_70M4lkLKPk