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.


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.


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.”


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: The Stars of Summer are Here

The Summer Triangle is high in the east.  This consists of the brightest stars in Cygnus, Lyra, and Aquila.  Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left.  Leo, the Lion, sets in the west.  From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest.  Venus now moves away from Jupiter as they both gradually become lost in the Sun’s glare

The Summer Triangle is high in the east. This consists of the brightest stars in Cygnus, Lyra, and Aquila. Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left. Leo, the Lion, sets in the west. From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest. Venus now moves away from Jupiter as they both gradually become lost in the Sun’s glare

This is the last month to observe the two brightest planets in the western evening sky. On June 30, Venus overtook Jupiter. This month, watch Venus shift to the left of Jupiter each evening at dusk. Meanwhile, both planets appear lower and lower to the horizon each night, until they are both lost in the Sun’s glare by the end of the month. At dusk, look over the point of sunset for the brightest objects there; Venus and Jupiter outshine everything but the Sun and the Moon.

Saturn is now in the southern sky at dusk. Although it is not as brilliant as Venus or Jupiter, it outshines the stars around it, so it’s also easy to see.

Mars remains lost in the glare of the Sun.

The Big Dipper is above and left of the North Star, with its handle pointing up. From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are in the southwest at dusk. Leo, the Lion, sets in the west at dusk.

Antares, brightest star of Scorpius, the Scorpion, is in the southeast, with the ‘teapot’ of Sagittarius rising behind it. Saturn is right above the scorpion’s head. The Summer Triangle has fully risen in the northeast. The stars of summer are here.


Moon Phases in July 2015:

Full July 1, 9:20 pm; July 31, 5:43 am
Last Quarter July 8, 3:24 pm
New July 15, 8:24 pm
1st Quarter July 23, 11:04 pm

At 2:41 pm on Monday, July 6, Earth is as far from the Sun as it will get this year, a moment known as aphelion. Remember, though, that the difference between aphelion and perihelion (in January) is small (only about 3%). Earth’s 23.5 degree tilt on its axis is a much more important effect. That’s why we have all this miserable heat and humidity now, rather than in January.

Just before 6:50 am CDT on Tuesday, July 14, the New Horizons spacecraft makes its closest approach to Pluto. As this is our first opportunity ever to gather real data from Pluto and its moons, astronomers are quite excited. The craft is already close enough to take some pictures, which you can see here. The Museum will have special activities for this occasion; email me if you want more information.

The Full Moon of July 31 is the second one of the month. That’s one of the definitions of a Blue Moon.

Planetarium Schedule:

Brazos Bend State Park, where our George Observatory is sited, has been closed since May 27 because the rains of Memorial Day and of Tropical Storm Bill caused the Brazos to overflow. The park plans to reopen on a limited basis July 8, making July 11 the first Saturday available for public observing.

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. I generally do one such tour on short June evenings.

Seeing Stars with James Wooten: The Stars of Spring are Rising

March star report
Mars remains in the west at dusk this month as it moves through Pisces. Mars continues to fade a little each night as Earth continues to leave it farther behind. After this month, Mars begins to be lost in the glare of the Sun.

Venus is in the west at dusk. Venus overtook Mars on February 21; now watch Venus leave behind the much dimmer Mars throughout March.

Jupiter was up all night long in February; now it is high in the east as soon as night falls. Jupiter outshines all stars we ever see at night, so it will be obvious in the east at dusk.

Saturn is in the south at dawn.

Brilliant winter stars shift towards the southwest during March. Dazzling Orion is almost due south at dusk. His three-starred belt is halfway between reddish Betelgeuse and bluish Rigel. Orion’s belt points up to Aldebaran in Taurus the Bull. To Orion’s upper left are the twin stars Castor and Pollux, marking the heads of Gemini, the Twins. You can find Sirius, the brightest star we ever see at night, by drawing a line from Orion’s belt towards the horizon. To Orion’s left, about level with Betelgeuse, is Procyon, the Little Dog Star.

From Sirius, look a little bit to the right and then straight down to the horizon. If your southern horizon is clear of clouds and tall earthly obstacles, you’ll see Canopus, the second brightest star ever visible at night. This star is so far south that most Americans never see it and many star maps made in the USA omit it. (You must be south of 37 degrees north—the latitude of the USA’s Four Corners—for Canopus to rise). As you view Canopus, keep in mind that the sky we see depends on our latitude as well as on time of year and time of night.

Joining the winter stars are stars of spring rising in the east. Look for Leo, the Lion at dusk. Later in the evening, extend the Big Dipper’s handle to ‘Arc to Arcturus’ and then ‘speed on to Spica’; these stars rise at about 10:00 in early March but by 9pm on the 31st.


Moon Phases in March 2015:

Full March 5, 12:05 pm
Last Quarter March 13, 12:48 pm
New March 20, 4:38 am
1st Quarter March 27, 2:43 am

Sunday, March 8, is the second Sunday of the month. Accordingly, Daylight Saving Time begins at 2:00 am on that date. (Officially, the time goes from 1:59 to 3:00 am). Don’t forget to spring forward!

At 5:45 pm on Friday, March 20, the Moon is directly overhead at the equator. This is therefore the vernal equinox. On this date everyone on Earth has the same amount of daylight and the same amount of night. The common statement that day equals night on this date would be true if the Sun were a point in our sky. Since the Sun is a disk about half a degree across in our sky, day is slightly longer than night on the equinox. For us, this is the ‘official’ start of spring; our days will continue to lengthen until the longest days of June usher in summertime. Below the equator, it is autumn, and days will continue to shorten until winter begins in June.

The New Moon of March 20 blocks the Sun, casting its shadow on the Earth. This results in a solar eclipse. Unfortunately, the shadow traces a path in the North Atlantic between Iceland and Scandinavia, making the eclipse inaccessible to us.

Click here for the full 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.

There’s a Partial Solar Eclipse Happening October 23: Here’s what you need to know to see it!


There’s a partial solar eclipse happening Thursday, October 23 and you can see it all from Houston*!

 The New Moon of Thursday, October 23, 2014, aligns with the Sun and the Earth well enough to cast its shadow towards Earth. However, no one will see a total eclipse for two reasons. First of all, the Moon was at apogee (greatest distance from Earth) on October 18, and is therefore smaller than usual in our sky. As a result, it is not quite big enough to cover the Sun, and the only eclipse possible would be an annular eclipse. Also, the Moon shadow is aligned to a point in space just over the Earth’s upper limb, so nobody will even get to see an annular eclipse. The near miss, however, allows the penumbra, where the Moon partially blocks the Sun, to land on the Earth. With North America near the upper limb of the Earth at the time, Houston will be within the penumbra. Therefore we will see a partial solar eclipse, in which the Moon will cover almost a quarter of the Sun’s disk at most.


At 4:59pm CDT, look for the Moon to take a ‘bite’ out of the Sun’s disk. The Moon covers the northern limb of the Sun, which is the right side of the Sun as it sets in the west. Maximum eclipse, with the Moon covering almost 1/4 of the Sun’s disk, is at 5:58.  At 6:43, the Sun sets while still in partial eclipse. After this, the next partial solar eclipse visible from Houston occurs August 21, 2017. 


Eclipse begins: 4:59 PM, CDT
Mid-eclipse: 5:58 PM
Sunset: 6:43 PM

The Museum’s own George Observatory in Brazos Bend State Park will be open to the public from 1:00 -6:00 p.m. on October 23 for observing the Sun and, starting at 5:00, the eclipse.  

*CAUTION: Never look directly at the Sun with the naked eye or through an unfiltered telescope. Permanent eye-damage will result.