Educator How-To: Identifying moon phases

The moon’s appearance in the sky follows a 29.5-day cycle. During the cycle, it first appears as a crescent. The lighted portion that you can in the night sky see becomes larger as days pass, growing until you see a full moon. As more days pass, the lighted portion gets smaller again, until no moon is seen. The cycle then repeats. This 29.5-day cycle corresponds to the time during which the moon makes one complete orbit around Earth.

When you see a full moon, Earth is between the moon and the sun, and all of the lighted half of the moon faces Earth. When there is a “New Moon.” the moon is between Earth and the sun, and all of the lighted half of the moon faces away from Earth. When there is a New Moon, you can’t see any of the moon at all.

Paper plates
Copies of moon phases (downloadable here!)
Jumbo craft sticks

Educator How-To:

Fold a paper plate in half and carefully cut out the middle of the plate with scissors.
Neatly cut out the moon phases and glue them to the rim of the plate starting with #1 in the 12 o’clock spot and working clockwise.
Staple a jumbo craft stick to the bottom of the plate.
Staple or glue the moon phase key to the handle of the plate.
At night, locate the moon. Holding the moon viewer with the stick pointing toward the ground, frame the moon within the center of the plate.  Observe.  Which picture does the moon most closely resemble? Find that number on the moon phase key and you will know the name for the phase of the Moon you are viewing!

Educator How-To:

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

Educator How-To: Making the Moon out of Cheese (and Crackers!)

Teach your students about the phases of the moon with this awesome Solar System snacking activity.

I created this lesson plan as an alternative to the Oreo™ phases of the moon activity that we think is so clever. This science snack is a healthier alternative and will satisfy hungry students without the sugar rush.

Educator How-To: Making the Moon out of Cheese (and Crackers!)

Moon worksheet


  • Ritz™ Crackers
  • American cheese slices
  • 1.5 inch round “cookie” cutter
  • Phases of the moon chart
  • Phases of the Moon worksheet
  • Markers
  • Waxed paper
  • Plastic knives

Educator How-To: Making the Moon out of Cheese (and Crackers!)

Moon phases


  1. Give each child a copy of the phases of the moon chart.  Go over the different phases, and consider using our Educator How-To: We’ll See You on the Dark (and Light and Far) Side of the Moon to demonstrate the phases in an active, hands-on fashion.
    2.    Distribute one slice of American cheese to each student.
    3.    Instruct students to carefully use the circular cutter to cut four circles from the cheese. With careful placement, one slice of cheese will be sufficient.
    4.    Using a plastic knife, students will then cut one circle of cheese in half.
    5.    The second circle will be cut using the circular “cookie” cutter.  Place the cutter carefully on the circle of cheese so that a crescent-shaped piece of cheese is cut from one side.
    6.    The same procedure should be used to cut an additional crescent-shaped piece from the third circle of cheese.
    7.    The fourth circle will remain whole.
    8.    Now you are ready to go! Distribute the Phases of the Moon worksheets and have students place a Ritz™ cracker on each “moon”.
    9.    Students will now arrange the cheese on the crackers to reflect each phase of the moon.
    10.    When finished, students may eat the tasty moon snack!

Go Stargazing! September Edition

Saturn leaves the evening sky in September 2011.  Face west southwest at dusk, and you’ll see Saturn near a star of similar brightness—Spica in Virgo.  Saturn is a bit to the right of Spica as you face southwest.

Each night this month, however, Saturn and Spica appear lower and lower to the horizon, until they set in twilight by mid-month.  When is the last night you can still see it?  Next month, Saturn is behind the Sun and invisible.

A Long Night Falls Over Saturn's Rings
Creative Commons License photo credit: NASA Goddard Photo and Video

Jupiter is now a late evening object.  It rises before 10:45 pm on September 1, and just after 8:30 pm by September 30.  Face east at the appropriate time and look for the brightest thing there—that’ll be Jupiter.   The King of Planets continues to dominate the southwestern pre-dawn sky.  Mars is now a bit higher in the east at dawn.  Although it has brightened, many of the stars in the morning sky outshine it.  However, as it moves from Gemini into dimmer Cancer, Mars is quite identifiable.  Venus was behind the Sun last month, and is still lost in the Sun’s glare.

Io Close-Up with New L8 Jupiter
Creative Commons License photo credit: FlyingSinger

The Big Dipper is beginning to pass under the North Star; Houstonians now need a clear northwestern horizon to see it at dusk.  From its handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars set in the west and southwest at dusk.  Antares, brightest star of Scorpius, the Scorpion, is in the southwest, with the ‘teapot’ of Sagittarius to its left.  Meanwhile, the Summer Triangle is virtually overhead.  The stars of summer now dominate the evening sky.  In late evening, you can watch the Great Square of Pegasus rise in the east.  Note that we look towards the center of our galaxy when we face between Scorpius and Sagittarius.  When facing the Great Square or especially south and east of that, we face out of the plane of our galaxy, a direction where there are fewer bright stars.  That’s why the large expanse of sky rising under Pegasus seems devoid of bright stars.

Moon Phases in September 2011:
First Quarter September 4, 12:39 pm
Full September 12, 4:26 pm
Last Quarter September 20, 8:39 am
New September 27, 6:08 pm

Autumnal Equinox

At 4:06 am CDT on Friday, September 23, the Sun is directly overhead at the equator.  This, then, is the autumnal equinox, a date when everyone in the world has the same amount of sunlight.  In the Northern Hemisphere, we’ve seen the days get a little shorter and the midday Sun a little lower each day since June 21.  For us, the season changes from summer to fall at the equinox.

In the Southern Hemisphere, people have seen the days lengthen and the midday Sun get a little higher each day since June.  For them, the season changes from winter to spring.

Rosh Hashanah

The New Moon of September 27 is the one closest to the fall equinox and therefore marks the Jewish New Year.  Rosh Hashanah is not on the New Moon itself but two days later on the 29th, when the slender crescent becomes visible in the west at dusk.

Astronomy Day 2011 at the George Observatory

Come join us anytime from 3 to 10 pm on October 8 for our annual Astronomy Day at the George Observatory. Dozens of telescopes—including our large research telescopes—will be available to give everyone a chance to enjoy the delights of the night sky, including star clusters, planets and galaxies.  Before dusk, we will have solar observing, Challenger Center simulations, outdoor and indoor presentations (beginning at 4) and many other activities!