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.

 

Seeing Stars with James Wooten: Mars and the Moon share the limelight

This star map shows the Houston sky at 10 pm CDT on April 1, 9 pm CDT on April 15, and dusk on April 30.  To use the map, put the direction you are facing at the bottom.  Jupiter is high in the west in Gemini, the Twins. Below them, Dazzling Orion, the Hunter sets with Taurus, the Bull.  To Orion’s left are the two Dog Stars—little dog Procyon and big dog Sirius.  Sirius outshines all other stars we see at night.  The Big Dipper is high in the north. Leo, the Lion, is high in the south. These stars, along with Arcturus, announce the spring.  Mars is up all night long this month.

This star map shows the Houston sky at 10 p.m. CDT on April 1, 9 p.m. CDT on April 15, and dusk on April 30. To use the map, put the direction you are facing at the bottom. Jupiter is high in the west in Gemini the Twins. Below them, Dazzling Orion the Hunter sits with Taurus the Bull. To Orion’s left are the two Dog Stars: little dog Procyon and big dog Sirius. Sirius outshines all other stars we see at night. The Big Dipper is high in the north. Leo the Lion, is high in the south. These stars, along with Arcturus, announce the spring. Mars is up all night long this month.

This month, Jupiter remains well placed for evening observing all spring. Look for it high in the west at dusk.

Mars is up virtually all night long this month. On April 8, Earth passes between the Sun and Mars. This places Mars at opposition, an alignment where we see Mars rise at dusk and set at dawn — Mars is up literally all night long. It turns out that Mars is farther from the Sun than average when Earth passes it, so at this opposition Mars is not as big or bright as in years past. Still, Mars now rivals the brightest star at night, Sirius, and is now as bright as it will get until May 2016.

Saturn remains in the pre-dawn sky. Face south right before sunup to see it. You can also begin observing Saturn in late evening. It rises just after 10:30 p.m. tonight, and then about a half hour earlier each night until by month’s end, it’s up until twilight. Saturn comes to opposition next month.

Venus remains in the morning sky. Look southeast at dawn for the brightest point of light there; only the Sun and Moon outshine Venus. Venus remains a morning star for almost all of 2014.

Brilliant winter stars shift towards the west during April. Dazzling Orion is high in the southwest at dusk. His three-starred belt is halfway between reddish Betelgeuse and bluish Rigel. Orion’s belt points right to Aldebaran in Taurus the Bull. Above Orion are the twin stars Castor and Pollux, marking the heads of Gemini the Twins. Jupiter is among the Twins this month. You can find Sirius, the brightest star we ever see at night, by drawing a line south from Orion’s belt (left as you face west). Forming a triangle with Betelgeuse and Sirius is Procyon the Little Dog Star.

Joining the winter stars are stars of spring in the south and east. Look for Leo the Lion almost overhead at dusk. In the east, extend the Big Dipper’s handle to “arc to Arcturus” and then “speed on to Spica.”

Moon Phases in April 2014:

1st Quarter: April 7, 3:31 a.m.
Full: April 15, 2:44 a.m.
Last Quarter: April 22, 2:52 a.m.
New: April 29, 1:17 a.m.

The Full Moon of Tuesday morning, April 15, fully enters the Moon’s shadow, causing a total eclipse of the Moon. The Moon first encounters the shadow at 12:58 a.m.; that’s when the partial phases begin. By 2:06 a.m., the Moon is all the way inside the shadow, and thus totally eclipsed. The Moon takes 78 minutes to cross the shadow, so totality lasts until 3:24 a.m.. The Moon then emerges from the Earth’s shadow until the eclipse is over at 4:33 a.m.

Keep in mind that the eclipse happens in the morning hours of Tues., April 15. Don’t go out looking for this Tuesday night! Our George Observatory will be open from sundown Mon., April 14 until dawn on Tues., April 15 for observing the eclipse. If you can’t come to the George at such early morning hours, remember that anyone who sees the Moon sees the eclipse. You can observe this eclipse from your backyard or even through your window if you have one that faces south/southwest.

The only thing that can stop you from seeing the eclipse is overcast weather. If we do get clouded out, or if you can’t get up in the middle of the night, we can observe another eclipse on Oct. 8, 2014, right before dawn.

Click here to see the HMNS 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!

Go Stargazing! July edition

Jupiter becomes a late evening object by the end of the month.  It rises in the southeast just after 11 p.m. on July 1, although you may need to wait awhile for it to clear trees or buildings in that direction.  By month’s end, Jupiter rises at 9 p.m. — in late twilight.  Early risers can still see Jupiter in the southwest before dawn.  Next month, Jupiter is in the sky literally all night long.  Remember, Jupiter outshines everything in the sky except the Sun, the Moon, and Venus, so if you’re looking in the right direction, you can’t miss it.

Venus is a dazzling morning star this month.  Look east right as day begins to break for the brightest thing unless the Moon is nearby.  Venus remains the ‘morning star’ for the rest of 2009.  Mars is a little higher in the east at dawn than it has been.  Still, it remains fairly dim.  Look for Mars above Venus and to its right.  This is quite a mismatched pair; Venus is about 100 times brighter than Mars.

Saturn portrait
Creative Commons License photo credit: Elsie esq.

Saturn remains well placed in the evening sky this month.  Look for it in the west at dusk.  If you have seen Saturn through a telescope this year, you may have noticed how much thinner the rings appear now than in years past.  This is because Earth is beginning to align with Saturn’s ring plane, making the rings appear edge-on from our perspective.  On September 4, the Earth is exactly in Saturn’s ring plane, and the rings actually vanish from view!  It turns out, though, that Saturn is too close to the Sun in our sky on that date; the Earth will be about to pass on the far side of the Sun from Saturn.  No one can get a good look at Saturn this September.  However, we can still watch through our telescopes as Saturn’s rings appear thinner and thinner throughout July and August.

Saturn’s moons orbit in the same plane as its rings.  Since we ordinarily have a perspective looking over one of Saturn’s poles, moons such as Titan and Rhea can usually appear above or below Saturn as well as to its right or left in a telescopic image.  These moons are not normally blocked by Saturn.  That changes, however, when Earth aligns with Saturn’s ring plane.  Now that we’re seeing the entire system edgewise, we’re beginning to see Saturn’s moons pass in front of and behind Saturn’s disk.  The passage of a moon in front of a planet’s disk is a transit, while an occultation occurs when a planet’s disk blocks a moon.  When a moon transits, we can often see its shadow on the planet’s disk.  Here are some upcoming events for Saturn and Titan as seen from Houston:

7/9        Titan is partly occulted (blocked) by Saturn until 9:30 pm.

7/17      Titan is already in transit as night falls; it leaves the Sun’s disk between 9:45 and 10:20. (Titan appears as a disk and not a point, so it takes some time to move all of the way off Saturn’s disk.  Saturn sets by 11:15.

7/25      Titan is occulted by Saturn.

8/2        Titan is in transit from dusk until Saturn sets.  Titan’s shadow appears on Saturn’s disk at 9:30.

8/10      Titan occulted by Saturn

8/18      Titan transits Saturn.

By August 18, however, Saturn is so close to the Sun in our sky that it is only about five degrees high during late twilight and sets before night completely falls.

M42 Orion
Creative Commons License photo credit: makelessnoise

Look high in the west at dusk for stars in the shape of a backwards question mark, with a right triangle to the left of that.  These stars are in Leo, the Lion.  Saturn is under the ‘right angle’ in that right triangle.  The Big Dipper is high in the northwest on summer evenings.  From the Big Dipper’s handle, you can ‘arc to Arcturus.’  Arcturus, in the west at dusk, is the fourth brightest star we ever see at night and will be the brightest star in our night skies during all of July. Continuing the curve of the Big Dipper’s handle past Arcturus, you can ‘speed on to Spica,’ a star lower in the southwest at dusk.  Spica is a stalk of wheat held by Virgo, the Virgin, who represents the harvest goddess.

In the south as night falls is Antares in Scorpius, the Scorpion.  This is a red super giant star about 700 times as wide across as our Sun.  To the Scorpion’s left, look for eight stars in the shape of a teapot.  These stars are the bow and arrow of Sagittarius, the Archer.  In the east, the Summer Triangle dominates the evening sky.  The Triangle is up all night long until mid-August.  Vega is the brightest of the triangle’s three stars, followed by Altair in Aquila and Deneb in Cygnus.

Moon Phases in July 2009:

Full                                   July 7, 4:21 am
Last Quarter                     July 15, 4:53 am
New                                  July 21, 9:34 pm
1st Quarter                       July 28, 4:59 pm

Eclipsed? Not totally.
Creative Commons License photo credit: James Jordan

The New Moon of July 21 lines up well enough with the Earth and Sun to cast its shadow on the Earth.  This causes a total solar eclipse.  The Moon’s shadow first encounters the Earth just north of Mumbai in India, so that’s where the path of totality begins.  From there, the shadow moves across Bhutan and then southern China, including Shanghai.  The shadow then ends up over the Pacific Ocean and leaves Earth before ever again reaching land.  The only part of the US anywhere close to this path is Hawaii, which experiences a partial eclipse.  This is mostly an event for Asia, where the date will be July 22.

The next total solar eclipse visible in the USA will occur August 21, 2017.

The Full Moon of July 7 almost enters the Earth’s shadow.  It does skirt the edge of the penumbra, in which the Earth partially blocks the Sun.  The resulting penumbral eclipse is scarcely noticeable at all, however.

At 3 a.m. on Friday, July 3, Earth is as far as possible from the Sun (i.e., at aphelion).  Planetary orbits are not perfect circles but ellipses.  Thus, Earth does not remain at the same distance from the Sun throughout its orbit, but gets slightly closer in January and slightly farther in July.  The difference is only about 3.4%, however—not enough to affect our seasons.  The change in seasons is due to the Earth’s tilt on its axis, not the distance from the sun.