Seeing Stars with James Wooten: Exciting Rare Mercury Transit Next Monday!

May Starmap

Jupiter is now high in the south at dusk. It outshines all stars we ever see at night, so you can’t miss it.

Mars and Saturn become late evening objects this month. Tonight, May 2, Mars rises in the southeast at 9:48 p.m. while Saturn comes up soon afterwards, at 10:24 p.m. By May 15, though, both planets rise during twilight, and on Memorial Day both are in the southeastern sky as soon as it gets dark. Mars and Saturn are still above the distinctive pattern of Scorpius, the scorpion. As you watch them rise, Mars is to the upper right and is much brighter.

In fact, this month, Mars outshines all of the stars and even rivals Jupiter in brightness! That’s because on May 22, Earth passes between the Sun and Mars. That alignment is called ‘opposition’ because it puts Mars opposite the Sun in our sky, making Mars visible literally all night long. It also makes Mars much brighter than normal in the sky, since we’re as close to it as we’ll ever get until Earth overtakes Mars again in 2018. Saturn comes to opposition June 3.

Venus is lost in the Sun’s glare and out of sight all month.

A swath of brilliant winter stars sets in the west at dusk. Orion, the Hunter, is still visible in the west as May begins. His two dogs, represented by Sirius and Procyon, are to his left.  Gemini, the Twins, are above Orion. The Big Dipper is above the North Star, with its handle pointing to the right. From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are high in the east and in the south, respectively, at dusk. Leo, the Lion, passes almost overhead at dusk.

As Orion and his dogs set, look for Antares, the brightest star in Scorpius, the Scorpion, to rise in the southeast. Saturn and Mars will rise with the Scorpion’s head, above Antares. At the same time, Vega, brightest star of the Summer Triangle, appears low in the northeast. These stars remind us that summer is on the way.

Moon Phases

Moon Phases in May 2016:

New: May 6, 2:30 p.m.

First Quarter: May 13, 12:02 p.m.

Full: May 21, 4:14 p.m.

Last Quarter: May 29, 7:12 a.m.

Mercury Transit:

On Monday, May 9, 2016, Mercury overtakes Earth on its much faster orbit. This time, though, when Mercury passes Earth, the alignment is almost exact, such that Mercury appears in silhouette against the sun’s disk. This event is known as a transit of Mercury. Keep in mind that the planets are almost, but not exactly, in the same plane. Indeed, Mercury’s orbit is the most inclined — tilted up to 7 degrees from Earth’s orbital plane. That’s why Mercury does not usually transit the sun when it overtakes Earth. Monday’s event is therefore rare and special, occurring only 14 times in the 21st century (the next one occurs Nov. 11, 2019).

Transit_of_Mercury_May_9_2016_path_across_sun

Thus, weather permitting, the Houston Museum of Natural Science has arranged for volunteers from local astronomy clubs to set up solar telescopes outside our museum’s main entrance, near the sundial, to show you the transit. Mercury, already in the sun’s disk by sunrise in Houston, takes until 1:42 p.m. to cross to the other side of the sun’s disk. If skies cooperate, we’ll observe the transit from 10 a.m. until 1:42 p.m. on Monday, May 9. If there are sunspots on the sun’s disk while Mercury is there, Mercury will stand out because its disk is fully round and because Mercury moves noticeably across the sun’s disk during the hours we’re watching.

We will observe the sun (and Mercury in silhouette) through telescopes with filters especially designed to filter the sun safely, and by projecting the sun’s image onto a screen. These are the only two ways to observe the Sun safely. Please do not try to observe the sun directly or through an unfiltered telescope, as this will lead to permanent eye damage or blindness. Our common sense tells us this because we always avert our eyes when we accidentally turn towards the Sun. When something cool happens on the sun, some of us try to override our common sense, and there is no reason to do so. Come observe safely with us.

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. As of now, George is closed which Brazos Bend State Park dries out from last month’s floods, and is scheduled to reopen May 10. If you’re there, listen for my announcement. 

Seeing Stars with James Wooten: Winter Stars Shift to the Southwest

This star map shows the Houston sky at 9 pm CST on March 1, 9 pm CST on March 15, and dusk on March 31.  To use the map, put the direction you are facing at the bottom.

This star map shows the Houston sky at 9 pm CST on March 1, 9 pm CST on March 15, and dusk on March 31. To use the map, put the direction you are facing at the bottom.

Jupiter comes to opposition on March 8, which is when Earth aligns with Jupiter and the Sun. That is why Jupiter is up all night long in early March. Face east in evening twilight to watch Jupiter rise. It outshines all stars we ever see at night, so you can’t miss it. Early risers will still see Jupiter setting in the west at dawn.

Venus is in the southeast at dawn, appearing lower to the horizon each morning this spring. Venus outshines all the stars we see at night, and in fact outshines everything but the Sun and the Moon. However, now it doesn’t rise until morning twilight, and will soon become lost in the Sun’s glare. How long can you follow it?

Mars is in the south at dawn. Noticeably reddish in tint, Mars continues to brighten each day until its opposition in May; it has now surpassed nearby Saturn in brightness.

Saturn is in the south at dawn, above the distinctive pattern of Scorpius, the scorpion. Mars slowly approaches Saturn this month.


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

Moon Phases in March 2016:

Last Quarter Mar. 1, 5:11 p.m.; Mar. 31, 10:17 a.m.

New Mar. 8, 7:54 p.m.

1st Quarter Mar. 15, 12:03 p.m.

Full Mar. 23, 7:01 a.m.

The New Moon of March 8 actually blocks the Sun, causing an eclipse of the Sun! However, it is visible only in Indonesia and the Pacific, where it will be March 9.

The Full Moon of March 23 passes though the penumbra, in which Earth partially blocks the Sun, but misses the true shadow or umbra. The resulting penumbral eclipse is only barely noticeable.

Sunday, March 13, 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 11:30 pm on Saturday, March 19, the Sun is directly overhead at the equator, shifting northward. That makes this the vernal (spring) equinox for us. Beginning on this date, day is longer than night for us in the Northern Hemisphere. Meanwhile, below the equator, days are shortening and now day is shorter than night. It is autumn down there.

On Friday, March 11, the brand new Burke Baker Planetarium re-opens to the public. Over Spring Break, come join us and enjoy images sharper than in any other theater!

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!

James G. Wooten
Planetarium Astronomer
Houston Museum of Natural Science

Seeing Stars with James Wooten: Lunar Eclipse on April 4

april stars

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

Mercury enters the evening sky as Mars leaves it. By April 30, Mars will be gone but Mercury will be low in the west northwest, near the Pleiades star cluster.

Venus is in the west at dusk. Look over the point of sunset for the brightest thing there.

Jupiter is now high in the sky, almost overhead, as soon as night falls. Jupiter outshines all stars we ever see at night, so it will be obvious when you look up at dusk.

Saturn is in the southwest at dawn.

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 from Orion’s belt towards south (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 2015:

Full April 5, 7:05 am

Last Quarter April 11, 10:44 pm

New April 18, 1:56 pm

1st Quarter April 25, 5:55 pm

The Full Moon of April 4 passes through the Earth’s shadow, causing a total lunar eclipse. Unfortunately, the Moon clips the edge of the Earth’s shadow, allowing for only 5 minutes of totality. What’s more, for us the eclipse occurs near moonset and sunrise (which are almost simultaneous when there is a lunar eclipse). That puts the Moon low to the horizon during the eclipse; only those with clear views all the way to the western horizon can get a good look. It also means that totality falls during morning twilight.

Eclipse times:

Partial eclipse begins: 5:15 am
Totality 6:57-7:02 am
Moonset (still partially eclipsed) 7:13 am

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.

Go Stargazing! May Edition

Saturn is the only planet in May 2011 evening skies.  Face south southeast at dusk, and you’ll see Saturn near a star of similar brightness— Spica in Virgo.  Saturn is significantly higher in the sky than Spica and a bit to its right as you face south.  Last month, Earth passed between the Sun and Saturn.  That alignment, called opposition, put Saturn in the sky all night long.  The ringed planet is now well placed for evening viewing, and remains in the evening sky until late September 2011.

mars-06-crop
Mars
Creative Commons License photo credit: chipdatajeffb

The other four naked eye planets are involved in a very close gathering low in the east at dawn.  You will need a clear view all the way to the east northeastern horizon at daybreak to observe this planet massing.  However, the planets do outshine all stars in this general area. If you’re able to observe any points of light just above the horizon as dawn begins, you’re probably seeing the planets.  As of now, Venus and Mercury rise first, with Mercury about a degree under the brighter Venus.  Mars and Jupiter are a bit to their lower left, with Mars a little to the left of Jupiter.  Mars was less that half a degree above Jupiter on May 1, and is now slowly pulling away from it.  Venus and Mercury are moving faster, so they are closing the gap on Mars and Jupiter.

On the morning of May 11, Venus and Mercury will be aligned with Jupiter, with Venus less than one degree from Jupiter.  This is also when the entire grouping is the most compact, with all four planets within six degrees of one another.  By May 21, Mercury and Venus will have caught up with Mars, with Venus just over a degree from the red planet.  After this, Mercury and Venus pull ahead of Mars and thus go deeper into the sun’s glare.  Mars and Jupiter, left behind, remain in the morning sky all summer.

Star Gazing
Creative Commons License photo credit: jurvetson

A swath of brilliant winter stars sets in the west at dusk this month.  Orion, the Hunter, is still visible in the west as May begins.  His two dogs, represented by Sirius and Procyon, are to his left.  To Orion’s right is Taurus, the Bull, with the star Aldebaran as its eye. Gemini, the Twins, are above Orion.  The Big Dipper is above the North Star, with its handle pointing to the right.  From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica;’ those stars are in the east and southeast at dusk.  Leo, the Lion, passes almost overhead in late evening.

As Orion and Taurus set, look for Antares, brightest star of Scorpius, the Scorpion, to rise in the southeast.  At the same time, Vega, brightest star of the Summer Triangle, appears low in the northeast.  These stars remind us that summer is on the way.

Moon Phases in May 2011:

New Moon                              May 3, 1:50 a.m.

1st Quarter                             May 10, 3:32 p.m.

Full Moon                               May 17, 6:07 a.m.

Last Quarter                          May 24, 1:51 p.m.