Once in a Red Supermoon: Watch Sunday’s rare lunar eclipse at the George Observatory

Our moon goes by many different names depending on the season and its position relative to the Earth. The evening of Sunday, Sept. 27, it will become three identities at once, an exceptionally rare occurrence. For the first time in 33 years, Earth will witness a total eclipse of the moon at its perigee near the autumnal equinox: a blood moon, a supermoon and a harvest moon combined. You can watch the eclipse of historic proportions anywhere on the planet where the moon is visible, but at the George Observatory, you can learn about eclipses while you catch it in action.

Houstonians will be able to see the whole event, which begins right as twilight ends. Lunar eclipses occur when the full moon moves into the Earth’s shadow. The first part of the Earth’s shadow the moon will encounter is called the penumbra. For our area, sharp-eyed observers will notice only a slight dimming of the moon between 7:10 p.m. and 8:07 p.m. Central Daylight Time (CDT). The moon moves into the darkest part of the Earth’s shadow, the umbra, at 8:07 p.m., and will be totally eclipsed by 9:10 p.m. Totality will last until 10:24 p.m. The moon will then exit the umbra and leave it completely by 11:27 p.m., when the eclipse ends.

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This diagram displays the movement of the moon through Earth’s shadow during the total eclipse. Times are shown in Eastern Daylight Time (EDT). For times in CDT, our time zone, subtract an hour.

The moon’s brightness during a total eclipse depends on the amount of dust particles in the atmosphere. A large amount of dust from a volcanic eruption, for example, can make the totally eclipsed moon almost invisible. With little dust in our atmosphere, the moon glows reddish-orange during totality. This is because only the sun’s red light comes through the Earth’s atmosphere and falls on the moon even while it is in the Earth’s shadow. As the diagram shows, the moon passes through the southern part of the shadow, for 74 minutes of totality. As a result, the northern limb, closer to the center of Earth’s shadow, will appear darker.

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Sunlight refracted through Earth’s atmosphere gives the moon its red color during a total lunar eclipse, also called a blood moon by many. This is the same red light you see at sunrise and sunset, but from the moon’s perspective. If you were standing on the moon during the eclipse, you would see a dark Earth ringed in a glowing halo of red.

You may have heard that this is a “supermoon eclipse.” That’s because this full moon happens less than one hour after the moon makes its closest approach to the Earth, called perigee. What’s more, this is the closest perigee of the year, 145 km closer than on Feb. 19.  At perigee, the moon is the biggest it can get in our sky, though the difference is only slight. Your pinky held at arm’s length still covers it up!

A supermoon eclipse is a rare phenomenon. The last one occurred in 1982, and there have been only five since 1900. After Sunday, the next one will occur in 2033. Compare this to a blue moon, or two full moons occurring in a month. The last blue moon occurred this year on July 31, and prior to that, on Sept. 30, 2012. Perhaps we should revise the phrase “once in a blue moon” to “once in a red supermoon.”

We can also call this a harvest moon since it’s the full moon closest to the fall equinox. Because the moon rises close to sunset for several days before and after the night of the full moon, its light allows harvesters to keep working instead of stopping at sundown. The fall equinox occurred Wednesday, Sept. 23, so this full moon is indeed the harvest moon, which makes this Sunday’s event a “harvest moon eclipse.”

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Our own George Observatory will be open Sunday night from 6 p.m. to midnight specifically for observing the eclipse. Here at the Houston Museum of Natural Science, our Starry Night Express shows in the planetarium will feature the eclipse. We’ll also give a preview of the event before every planetarium show that weekend. If you can’t join us here or at the George, just remember that whoever can see the moon can see the eclipse. You can therefore watch the eclipse from your front or back yard, or even out the window if it faces the right angle! Only overcast skies can stop you from seeing the eclipse. Let’s hope our current trend of clear skies holds through Sunday.

This is the last of four lunar eclipses last year and this year, all total, and all visible from North America. That series ends here; in Houston, we’ll see our next total lunar eclipse at dawn Jan. 31, 2018.

Seeing Stars with James Wooten: Total Lunar Eclipse this Month

Stars

Saturn is now in the southwestern sky at dusk. It outshines the stars around it, so it’s also easy to see. 

Mars is a little higher in the morning sky this month. Look for it low in the east at dawn. Mars remains dimmer then average, though, and won’t rival the brighter stars until next spring.  

Venus and Jupiter reappear in the morning sky this month. Venus is already visible in the east at dawn; Jupiter will join it after the middle of the month. Venus outshines everything but the Sun and the Moon, while Jupiter is next brightest after Venus. Both, then, easily outshine all the stars we see at night and are clearly visible even in twilight.

Venus, Mars, and Jupiter will come close together in the sky late next month.

The Big Dipper is left of the North Star, with its handle pointing up. From that handle, you can ‘arc to Arcturus’ in the west at dusk. 

Antares, brightest star of Scorpius, the Scorpion, is in the southwest, with the ‘teapot’ of Sagittarius to its left. Saturn is to the right of the scorpion’s head. The Summer Triangle is overhead. The Great Square of Pegasus is now in the east, indicating the approaching fall.

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Moon Phases in September 2015:

Last Quarter: Sept. 5, 4:54 a.m.

New: Sept. 13, 1:41 a.m.

First Quarter: Sept. 21, 3:59 p.m.

Full: Sept. 27, 9:50 p.m.

The Full Moon of September 27 enters the Earth shadow, causing a total lunar eclipse. Partial eclipse begins at 8:07 pm CDT, about an hour after sunset and right as twilight fades. The Moon is totally eclipsed by 9:10. Totality lasts 74 minutes, until 10:24. The Moon then comes out of eclipse until the eclipse is over at 11:27. This is the last of a series of four total lunar eclipses in 2014-2015, all visible from Houston. Unlike the previous three, which occurred at midnight or at dawn, this eclipse takes place in evening hours while everyone is still awake. Remember, whoever can see the Moon can watch the eclipse. Let’s hope the weather cooperates and we can all enjoy it. Our George Observatory will be open Sunday evening, September 27, for this event.

If we miss this eclipse, the next one we can see is at dawn Jan. 31, 2018.

At 3:21 a.m. on Wednesday, Sept. 23, the Sun is directly overhead at the equator, shifting southwards. This, then, marks the autumnal equinox, the ‘official’ start of fall. On this date (and on the spring equinox in March) everyone on Earth has the same amount of daylight.  After this date, night is longer than day for us and keeps getting longer until our longest night at the winter solstice. Below the equator, day becomes longer than night after this equinox. It is springtime down there. 

Planetarium Schedule

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. If you’re there, listen for my announcement.

Clear Skies!

Blood Moon Strikes Back! Total Lunar Eclipse Wednesday, October 8!

A total eclipse of the Moon will occur early Wednesday morning, October 8. Houstonians will be able to see virtually the whole event, which happens right before dawn.

Lunar eclipses occur when the full Moon moves into the Earth’s shadow. The first part of the Earth’s shadow that the Moon will encounter is the penumbra. The penumbral shadow’s faintness means that sharp-eyed observers will notice only a slight dimming of the Moon between 3:14 AM and 4:15 AM. The Moon moves into the darkest part of the earth’s shadow, the umbra, at 4:15 AM, and will be totally eclipsed by 5:24 AM. Totality lasts until 6:25, at which time the Moon has crossed the shadow and begun emerging from the other side. The Moon is still emerging from the shadow (and thus still partially eclipsed) as it sets at 7:26.  Note that this eclipse happens close to dawn, which is when a Full Moon is about to set. Therefore, you’ll need an observing site clear of obstacles to the west so you can watch the setting Moon in eclipse.  (That’s why we’re not observing from George Observatory, as we have in the past. Our tree line would interfere with the view).

Eclipse Diagram - James Wooten

The Moon’s brightness during a total eclipse depends on the amount of dust particles in the atmosphere. A large amount of dust from a volcanic eruption, for example, can make the totally eclipsed Moon almost invisible. With little dust in our atmosphere, the Moon glows reddish-orange during totality. This is because only the Sun’s red light comes through the Earth’s atmosphere and falls on the Moon even while it is in the Earth’s shadow. As the diagram shows, the Moon will pass through the northern part of the shadow, for about an hour of totality. As a result, the southern limb, closer to the center of Earth’s shadow, will appear darker.  And since we’ll be watching the Moon set in the west, the northern limb will be to the right and the southern limb to the left.

This is the second of four consecutive total lunar eclipses in 2014 and 2015, all of which are visible in the USA.  We’ll see our next total lunar eclipse in Houston just before dawn on April 4, 2015.

 

A total eclipse over Houston: What color was last night’s ‘blood Moon’?

I hope you saw the eclipse last night and didn’t lose too much sleep. The weather was perfect and the Moon performed as predicted. The press excitedly dubbed it a ‘blood Moon,’ but we didn’t know what color the Moon would actually be.

Here’s the Moon entering eclipse and fully in the Earth’s shadow (taken from my front yard). Is it a ‘blood Moon’ after all? You be the judge.

Photo by Gary Young. All rights reserved.

Photo by Gary Young. All rights reserved.

These photos were taken by my husband, Gary Young. (I was the frozen assistant.) We used a Takahashi FCT-76 telescope and a Canon 60D camera to capture the photos.

It was a spectacular eclipse, with Mars nearby to the right and Saturn off to the left. Both planets were very bright and easy to identify. The star near the Moon (and just off the field of these images) was Spica in the constellation Virgo.