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Star Teacher March 2008
Watch the Sun on March 20th
What direction do you look at if you want to see the sun rise? What about if you wanted to see it set? If you answered “east” for the sunrise and “west” for the sunset you’re right, but only for two days of the year! One of those days happens on March 20 this year and is known as the vernal equinox.
The word “equinox” comes from Latin and means “equal night.” An equal night is exactly what happens during an equinox: both the day and the night are the same length. Day and night are equal lengths only on the equinoxes because of the Earth’s axis. The Earth is always rotating around a lot like a top. As it spins, the axis of its spin keeps solidly aligned with the stars. In fact, the tip of its axis always points tot the same spot in the sky and that is where we see the North Star!
The weather would remain boringly constant, and no seasons would pass, if earth persisted in only this range of movement. Nigh and day would remain the same length and the sun would pass across the sky following the same path every day. The second major motion of the earth- its orbit or revolution around the sun- combines with our planet's tilt to make the sun's height and path change daily. That is the source of the seasons.
When the Earth is in the part of its orbit where the northern hemisphere is not facing the sun too directly, we have winter here in Maine. During this time the sun looks like it’s rising and setting a little bit south of east and west. Six months later, on the other side of our orbit, the northern hemisphere is facing the incoming sunlight more directly and we have summer. Then the sun looks like it’s rising and setting a little bit north of east and west and its path across the sky is much longer in distance and hours of daylight.
On the days of the equinoxes, though, the Earth is midway between those other extremes. This makes it so the sun shines directly on the middle of the Earth (passing directly overhead for residents on the equator). |
For more information about the science behind the equinox visit the Science World equinox page.
Your students can see the changes in the sun for themselves by exploring the Sunset At Home. Click on the image below for a printer-friendly PDF version of this activity.
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What's Happening in the Sky This March?
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New Moon – The darkest night of the month makes this the best time for viewing dimmer stars |
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Daylight Savings Time – Don’t forget to set your clocks ahead an hour! You will lose an hour of sleep but gain an extra hour of sun in the evening. |
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Ides of March – The fifteenth day of March in the ancient Roman calendar. This calendar was based on the phases of the moon. The Romans believed that the Ides of March fell upon the day of the full moon. |
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Spring/Vernal/March equinox – The day on which the sun rises directly east and sets directly west. |
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Full Moon – The full moon will light up the nighttime sky, making it difficult to see some of the dimmer stars. |
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Easter Day – Easter falls upon the first Sunday after the first full moon after the spring equinox. |
Where Are the Viewable Planets?
| Venus |
Look for Venus low in the Eastern sky during the wee hours of the morning. If you have binoculars you may be able to catch Mercury as well. On the 23, 24, and 25 the closest planet to the sun will be within one degree of Venus. |
| Mars |
Mars will move eastward across the sky during March, making its way halfway across Gemini by the end of the month. The red planet will fade in brightness over the course of the month but can still be easily seen. |
| Jupiter |
Get up early to see this bright planet: it won’t rise until a few hours before the sun does. Look for this planet in the constellation of Sagittarius and be careful not to confuse it with Venus! |
| Saturn |
Saturn will be bright and easy to see through most of the night. Look for it near Regulus (the heart star of Leo the lion). For viewers with telescopes Saturn will be sharpest in the late evening. |
CLICK image for pdf planet charts
 
Click for a March star map
Beware the Ides of March!
When most people hear the phrase “Ides of March” they think of Julius Caesar and the ancient Romans. Did you know that the Ides of March also has something to do with space? The ancient Romans used a calendar that is very different than the calendar we used today. Their calendar wasn’t based on the sun like ours is. Instead, it was based on the phases of the moon.
To the Romans, the first day of the month was called “Kalends,” which comes from the Latin word calare (to cry out). This is where we get the word “calendar.” |
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A Roman month began on the day of the new moon. A special priest watched the sky in order to see when the moon was new. When he saw a new moon he would cry out that a new month has begun. After he called out the first day of the month the priest would calculate the date of the first quarter moon. This day of the month is known as “Nones.” Finally the priest would figure out which day the full moon would fall on. That day was supposed to be a very special day and was called “Ides.” The ides of a month usually fell on the thirteenth or the fifteenth, so the Ides of March is actually another way of saying March fifteenth.
The Romans stopped using this calendar around 500 BC. Over the years calendars changed as different cultures spread around the world. Now there are several different calendars in use. Today the United States uses the Gregorian calendar, which is one based on the sun.
Your can watch the skies like the Romans did with this printer-friendly moon watching activity. (Adobe Acrobat Reader Req'd)
For more in-depth information about Roman lunar calendars take a look at Calendars Through the Ages |
Help Fight Light Pollution This Week!
The United States by night |
For most of human history people have been able to look up at the sky and see the stars. As more and more people begin living in cities, however, it becomes harder and harder to see the beauty of the night sky. The bright lights that come from cities often create light pollution. City lights wash out the night sky, making it hard to see the stars, planets, and galaxies that fill the sky at night. Conservationists, astronomers, and sky watchers around the world want this to change and they need your help to do so!
You and your students can participate in a world-wide light pollution study at this month. Visit the Globe at Night webstie to find all the materials you'll need. This activity is an excellent introduction to the night sky for younger students. The event only runs through March sixth so act fast! |
This Month's Constellation: Canis Major
In the month of March the night sky is guarded by a watchful dog known as Canis Major. This canine constellation is easy to find in the southern sky soon after sunset. Take a look about halfway between the horizon and the zenith (the highest point in the sky) and you'll find a star that looks much brighter than any other around it. This star, called Sirius, is the brightest star in Earth's nighttime sky.
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Canis Major can be found following his master, Orion the hunter. Although there are no specific stories about Canis Major in Greek mythology, the star Sirius is often associated with the sun. Sirius is near the sun during the summer months, and it was thought that the star added to the sun's heat. This added heat was thought to make even dogs go crazy more than usual in the intense summer sun, which led to Sirius being called “the dog star” and the constellation it was in “the big dog.” Even now we call very hot days “the dog days of summer.”
On this month's star chart look for canis major close to the southern horizon.
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March Anniversaries
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13 – Uranus discovered: In 1690 the planet Uranus was thought to be a star in the constellation Taurus. It wasn’t until astronomer William Herschel observed the planet through a telescope almost a century later that its real identity was discovered. At first Herschel thought that Uranus was a comet, but after more observation of its movements astronomers decided that it was a planet. Uranus was named after Ouranos, the Greek god of the sky. During March Uranus is so dim that it cannot be seen with the naked eye. |
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14 – Einstein born: Albert Einstein was a German-born physicist who is most famous for his theories on space, time, and the nature of light. Although he suffered from a speech defect as a young child, he showed great skills in science and mathematics and was at the top of his class. The many scientific discoveries he made over his life led to him being honored with a Nobel prize for physics and named Time Magazine’s Man of the Century. |
Cassini Space Probe Flies By Saturn's Moon
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The planet Saturn is bright in the sky this March, but people on Earth aren't the only ones getting a good look at this planet. The space probe Cassini will get an up-close view of one of Saturn's moons. This moon is called Enceladus and is the sixth largest of Saturn's 60 known moons. Although it's the sixth largest it's still very small compared to Earth's moon, only 500 kilometers in diameter. Right now it's doing something that is making astronomers very interested: it's sending large bursts of steam and ice crystals out into space. |
Volcanic activity like this is very rare in small, icy moons like Enceladus. Moons of that size usually don't have enough energy to cause eruptions. Astronomers hope to find out what's making these eruptions when the Cassini probes makes a close fly-by of Enceladus's surface. On March 12 Cassini will swoop as close as 30 kilometer's away from the moon's surface. And that's not all! Astronomers hope to send Cassini through one of the plumes of gas that Enceladus is giving off.
Going through one of these plumes of gas is dangerous for Cassini, but the direction it will be heading in will protect it. The sensitive instruments that Cassini will use to learn more about the moon will be shielded by the body of the spacecraft. While it's in the plume the probe will take pictures of where the jet of gas is coming from. It will also do tests to find out what other chemicals might be found in the plume. |
Over the next few months the Cassini will continue to fly by Enceladus and other moons of Saturn. You can find out more about these moons and the planet they orbit around at the Jordan Planetarium show “Ring World.”
Click here for more information about Cassini's flight through Enceladus's plume, or here for information about the Cassini mission in general.
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