Seeing Stars with James Wooten: Venus shifts to morning, Chinese New Year approaches

This star map shows the Houston sky at 90 pm CST on January 1, 8 pm CST on January 15, and 7 pm on January 31.  To use the map, put the direction you are facing at the bottom.  The Great Square of Pegasus sets in the western sky. Taurus, the Bull, is almost overhead.  Dazzling Orion, the Hunter is high in the southeast, with his two dogs behind him.  Sirius, the Big Dog Star, is the brightest star we ever see at night.  Jupiter, in Gemini, is up all night long in early January.  In the north, the Big Dipper gradually re-enters the evening sky.

This star map shows the Houston sky at 90 pm CST on January 1, 8 pm CST on January 15, and 7 pm on January 31. To use the map, put the direction you are facing at the bottom. The Great Square of Pegasus sets in the western sky. Taurus, the Bull, is almost overhead. Dazzling Orion, the Hunter is high in the southeast, with his two dogs behind him. Sirius, the Big Dog Star, is the brightest star we ever see at night. Jupiter, in Gemini, is up all night long in early January. In the north, the Big Dipper gradually re-enters the evening sky.

This month, Venus shifts from the evening to the morning sky. For the next few days, look for it low in the southwest at dusk. If no buildings or trees block the view, you can still make out Venus in the twilight; it outshines everything in the sky but the Sun and the Moon. Notice how it appears lower on the horizon each night and is soon completely gone.

On Jan. 10, Venus passes between Earth and Sun (“inferior conjunction“), which would normally make it invisible to us. This time, however, Venus passes above the Sun from our perspective, which means the sharp-eyed observers with clear horizons can observe Venus both at dawn and at twilight for a few days around Jan. 10. After this, you can watch Venus emerge in the morning sky, visible in the southeast at dawn.

Venus remains a morning star for almost all of 2014.

Mercury briefly enters the evening sky this month, right as Venus leaves. Look for it low on the horizon during the last half of January. Although not nearly as bright as Venus, it easily outshines the dim stars near it. Thus, any “star” you see in twilight over the point of sunset late this month is probably Mercury.

Jupiter will remain well placed for evening observing all winter and into the spring (as the Earth passed between it and the Sun on Jan. 5). Look for it in the east at dusk and almost overhead later in the evening.

Mars remains in the morning sky. It continues to brighten a bit in the southwest at dawn.

Saturn has reappeared in the pre-dawn sky. Face south-southeast right before sunup to see it.

In January, the Big Dipper is only partly risen at dusk. As the Big Dipper sets, though, Cassiopeia rises. This is a pattern of five stars in a distinct W (or M) shape which lies directly across the North Star from the Big Dipper. Look for Cassiopeia high in the north on fall and winter evenings.

Watch for the Great Square of Pegasus in the west at dusk. Taurus the Bull is high in the south. Look for the Pleiades star cluster above reddish Aldebaran. Dazzling Orion the Hunter takes center stage on winter evenings. Surrounding Orion are the brilliant stars of winter.

Orion’s belt points down to Sirius, the Dog Star, which outshines all other stars we ever see at night. The Little Dog Star, Procyon, rises with Sirius and is level with Orion’s shoulder as they swing towards the south. To the upper left of Orion’s shoulder is Gemini, the Twins, which contains Jupiter this winter.


Moon Phases in January 2014:

New: Jan. 1, 5:15 a.m.; Jan. 30, 3:40 p.m.
1st Quarter: Jan. 7, 9:40 p.m.
Full: Jan. 15, 10:53 p.m.
Last Quarter: Jan. 23, 11:21 p.m.

At 5:59 a.m. on Sat., Jan. 4, the Earth is as close to the Sun as it will get this year; this is called perihelion. Keep in mind that Earth’s orbit is so close to being a perfect circle that its perihelion distance is 0.98 AU, where 1 AU (astronomical unit) is defined as the average Earth-Sun distance. This 2% difference is too small to influence our seasons; the tilt of the Earth’s axis toward or away from the Sun dominates this small effect. That’s why it’s so cold right now (even here in Houston!) and so hot in July.

Although the winter solstice is the shortest day, the earliest sunset occurred on about December 2, and the latest sunrise will occur January 10. That’s because the Earth speeds up on its orbit near perihelion. This acceleration shifts sunrise, local noon, and sunset slightly later each day at this time of year. The effect is smaller than that of the Sun taking a low path across the sky, which normally dominates in causing earlier sunsets and later sunrises. But the Sun’s apparent path varies very little near the solstice itself, allowing the secondary effect of the Earth being nearer to the Sun to predominate.

For most people, then, (those who witness sunset but sleep through sunrise), days will seem to lengthen much more than they actually are. Early risers, on the other hand, will find sunrise occurs even later than last month, at least until late January.

The New Moon of Jan. 30 is the second New Moon after the winter solstice. It therefore marks Chinese New Year. On this date, the Year of the Snake ends and the Year of the Horse begins.

Visit the HMNS website to see this month’s 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. We’re also hosting telescope classes on Jan. 11, so if you or someone you know received one over the holidays come by and let us help you set it up!

Seeing Stars with James Wooten: February 2013

Mercury briefly enters the evening sky this month. Greatest elongation (the greatest apparent distance from Sun) is February 16, so that’s when you’ll see it the longest.  However, you can begin looking in a few days. Because Mercury sets soon after the Sun, you’ll need a perfectly clear horizon right over the point of sunset at dusk.  On February 8, Mercury passes less than one degree from Mars, which is on its way out of the evening sky.

Jupiter was up all night long last month and is now almost overhead at dusk. Opposition, when Earth passed directly between Jupiter and the Sun, was January 3. Face high in the south at dusk and look for the brightest thing there (unless the Moon is also there), as Jupiter outshines all stars we ever see at night.

Sky Map: February 2013

Venus now rises while dawn brightens the sky; its morning apparition is ending. Soon Venus willl pass around the far side of the Sun from our perspective, and then reappear in the evening by summer.

Saturn remains in the morning sky this month. Look for it in the south-southwest at dawn.

Brilliant winter stars dominate the southern skies of February. 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. This winter the Bull also contains Jupiter.

Rising with Orion, and far to his 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.

Moon Phases in February 2013:
Last Quarter                  February 3, 7:57 am
New                               February 10, 1:22 am
1st Quarter                    February 17, 2:30 pm
Full                                February 25, 2:28 pm

The New Moon of February 10 is the second New Moon after the winter solstice.  Accordingly, it marks Chinese New Year. On this date the Year of the Dragon ends and the Year of the Snake begins.

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.

To enjoy the stars in any weather from the comfort of the HMNS Planetarium, click here for a full schedule.

Would you like email updates on current events in the sky, at the planetarium, and at the George Observatory?  If so, send an email to astroinfo@hmns.org.

Rabbit in the Moon

The new moon of Thursday, February 3, was the second new moon after the winter solstice and therefore marked the Chinese New Year, beginning the Year of the Rabbit. The full moon of Friday morning, February 18, just followed the fifteenth day of the first Chinese lunar month, which is known as the Lantern Festival.

The start of this year, then, is an ideal time to look at the features on the moon and see if you can find the “moon rabbit.”  Of course, there is no rabbit in the moon, just dark splotches which some people believe look like a rabbit.  Understanding the rabbit in the moon, then, involves understanding why the moon has dark and light features.

Oceanus Procellarum is the large mare in the center and upper left of this image.
Visible in the upper right is another large mare, Imbrium, and below is the small
round Mare Humorum.

Dark and Light

The moon is not of uniform brightness because it is not of uniform elevation.  The brighter regions are called highlands because they are higher than the darker regions.  Because early lunar observers mistook these dark areas for earthly seas, they are called maria (singular mare; pronounced ‘mah-ree-a’ and ‘mah-ray’), from the Latin word for ‘sea.’   One mare which is much larger than the others has the name ‘Oceanus Procellarum,’ as an ocean is bigger than a mere sea.  Similar, smaller features bear the names lacus (‘lake’) or sinus (‘bay’).  These terms have persisted long after we realized that the Moon has no liquid water and no oceans, seas or lakes.

Lunar Prospector
Image courtesy of NASA

Ancient Basaltic Lava

Lunar mare are in fact ancient basaltic lava flows which filled basins of very large caters on the moon.  Evidence based on radiometric dating indicates that the maria formed between 3.15 and 4.2 billion years ago, with most of the lava flows occurring between 3.15 and 3.8 billion years ago.  This would mean their formation followed the Late Heavy Bombardment (4.1 to 3.8 billion years ago), when countless planetesimals collided with the inner planets of our solar system, forming many craters.  It appears that during this period, some of the larger impacts fractured the lunar regolith.  A few million years later, basaltic lava flowed into the resulting basins.

Why do all the moon’s maria face Earth?

The maria are not spread evenly across the moon’s surface, but instead are almost all on the near side of the moon, which always faces Earth.  The reason for this is a topic of active debate and research among lunar scientists.  Data from the Lunar Prospector mission indicates that under the lunar crust is a layer abnormally high in potassium (K), phosphorous (P), and rare earth elements (REE).  Further, this KREEP material is not spread evenly across the moon but is instead concentrated on the near side, specifically in the Oceanus Procellarum and Mare Imbrium basins.  As potassium and the rare earth elements uranium and thorium are heat-producing, their presence may have favored basaltic lava flows on the near side as opposed to the far side.

Naming Lunar Geography

The mare names we use today go back to Italian Jesuit astronomers Giovanni Battista Riccioli and Francesco Maria Grimaldi.  In 1651, Grimaldi prepared a map of the moon which Riccoli published in his Almagestum Novum.  Folklore associating the first quarter moon with calm weather and the last quarter moon with storms influenced Riccoli as he named the features Grimaldi had drawn.  The western limb of the moon, visible at first quarter, has seas of  Tranquility, Serenity and Fertility (Fecunditatis).  The eastern limb of the moon, visible at last quarter, has seas of Rain (Imbrium), Clouds (Nubium)  and Moisture (Humorum), as well as an Ocean of Storms (Oceanus Procellarum).  Riccoli was not the first to name features on the moon; Michael van Langren and Johannes Hevelius had used different sets of names.  However, when later lunar mapmakers, such as Johann Schröter, used Riccoli’s names, they became standard.  Incidentally, Riccoli also labeled the lunar highlands as terrae (‘lands’), but that nomenclature has not continued to this day.

Moon Legends

Many people around the world have tended to make various pictures out of the darker regions on the Moon’s surface.  The scientific term for our tendency to imagine familiar figures on the moon, or in clouds, on trees, etc., is pareidolia.  Perhaps you are familiar with the man in the moon.  His face consists of Mare Imbrium and Mare Serenitatis (eyes) along with Mare Nubium (mouth).

The Chinese, however, imagined a rabbit in the moon.  Mare Nectaris and Mare Fecunditatis form the tips of the rabbit’s ears, which come together at Mare Tranquillitatis.  Mare Serenitatis marks his head.  The large maria Oceanus Procellarum and Mare Imbrium form the bulk of his body, with Mare Vaopurm as his forelegs and Mare Nubium and Mare Humorum as his hind legs.

In an alternate image, the rabbit is facing the east (left) limb of the moon and is running instead of sitting.  In this view, the head becomes Oceanus Procellarum and the main part of the body Mare Imbrium.  The ears of the previous rabbit, mare Fecunditatis and Mare Nectaris, become the hind legs of this one.  Mare Nubium and Mare Humorun are now forelegs.  Mare Frigoris, a long ‘sea’ near the northern limb of the moon which did not figure into the previous rabbit, becomes a long ear of this one.

Photo edited by Zeimusu:
The rabbit stands by a cooking pot.
Based on the public domain moon image from
image:Luna_nearside.jpg and information on the web.

In Chinese folkore, this is the Jade Rabbit, making the elixir of life for the goddess of the moon Chang’e. In Japan and Korea, the moon rabbit makes rice cakes.  A Buddhist legend tells that the monkey, otter, jackal, and rabbit resolved to offer food to a stranger passing through the forest on the night of the full moon.  The rabbit, able to gather nothing but the grass he ate, offered his own body instead, and was rewarded by being placed in the moon.

Asian societies were not alone in imagining a rabbit in the moon.  In Aztec legend the god Tecciztecatl became the moon god after he hesitated to sacrifice himself in fire to become the sun god.  As punishment, the gods decided the moon would not be as bright as the sun. The Maya also associated a rabbit with their moon goddess.

Today, our Easter holiday is associated with bunnies.  That holiday bears a pre-Christian name which the Venerable Bede attributed to a goddess Eostre, who was associated with rabbits (among other symbols of life and fertility).  Perhaps finding the rabbit in the full moons of March and April can put you in the spirit of the Easter holiday.

Festivals of the World at HMNS Sugar Land

Come join us this Saturday, December 11 from 10 a.m. til 2 p.m. at HMNS at Sugar Land for our Second Saturday event Festivals Around the World.

In cooperation with PACE (Parents for Academic Excellence), the Houston Museum of Natural Science at Sugar Land will help children appreciate 7 different cultures from around the world and what makes each one unique. Each culture will have a display, crafts and story time.

For Chinese New Year you will see Chinese clothing, a table setting, zodiac animals and pictures of Chinese New Year celebrations around the world. Participants will learn about the Chinese zodiac, make a zodiac card and complete a zodiac word search.
Story time will feature information about the Chinese Dragon Dance.

The Hanukkah display will feature clothing and jewelry for the holidays, decorations for the holiday season and an example of a traditional meal. For crafts, children will create a Menorah using their hands as patterns and a paper dreidel.

The Cinco de Mayo celebration will feature traditional Pueblan clothing, a display of Cinco de Mayo party decorations and a demonstration of the traditional way of making salsa. Visitors will make a papel picado, which is a type of traditional Mexican folk art.
Story time will feature a Mexican dance!

The festival known as Eid will feature displays of a prayer rug, the Koran, colorful illuminations, crescent moon, patakas (religious flags) and gifts. For crafts, children will make an Eid greeting card and a personal prayer rug.

The Kwanzaa display will feature a traditional table setting with an explanation of what each item means for the holiday. You will see decorations, food, flags, a Unity Cup and much more. Children will make an almost beaded headband.

The Diwali festival will feature clothing and jewelry for the holiday as well as traditional decorations for the holiday season. The craft will be making a paper lantern.
Story time will feature an Indian dance.

The Christmas season will feature displays of holiday items and decorations. For the crafts, children will make reindeer from their footprints and handprints and create a Christmas card using their fingerprints.
Story time will feature Christmas pop-up books.

Parents, bring your camera! Santa will be at the Houston Museum of Natural Science at Sugar Land for the Second Saturday celebration of Festivals Around the World.

This event is included with the price of admission to HMNS at Sugar Land.