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By Juan Ivaldi, August 10, 2011 6:57 am

Imagine an impact between the Earth and a tiny rock the size of a grain of sand.  The outcome of such an impact is one of the most exciting sights in the night sky, a shooting star.  The accepted term for a shooting star is a meteor.  When Earth passes through a stream of such particles in space, it produces what is known as a meteor shower.  One of the best observed of such showers is the annual Perseid meteor shower which will peak on the 13^th of August in 2011.  Following up on my last post, this meteor shower is a great opportunity to share the sky with kids.

The Perseid meteor shower is an annual shower occurring in mid-August when the Earth plows through the debris stream left behind by comet Swift-Temple.  The reason for the name is that the meteors from this shower appear to come from the constellation Perseus.  According to NASA, the little bits of comet dust slam into Earth’s upper atmosphere at 140,000 miles per hour.  At this high velocity, the dust burns up as it enters the atmosphere and the heat released produces a beautiful glowing streak in the sky as the particle vaporizes.  During a meteor shower such as the Perseid shower, you can see many meteors in a short time span.

One of the great things about observing meteor showers is that you don’t need any equipment to view them.  Just go outside and look up.  You are likely to see dozens of meteors per hour near the peak time of the shower.  This year the full Moon will be in the sky at the time of the Perseid shower.  The Moon’s glare will make it harder to see the fainter meteors, but you are likely to still easily catch the brighter fireballs.  These fireballs are memorable when they happen and are caused by the larger pieces of comet debris entering our atmosphere.  Some of these are bright enough to cast a shadow.

Perseid meteors will start appearing as soon as Perseus rises above the eastern horizon around 10pm and continue until sunrise.  The peak meteor activity is expected on the night of Friday, the 12^th of August through early Saturday morning (13^th).  Because the debris stream is wide, meteors can be observed on the days around the peak as well.  In fact, the meteor shower has already started as of the time of this post.  So, take the opportunity to go outside, share the sky with your child, and enjoy the meteors!

In summary:

What dates to look:  Peak Perseid meteor activity is on the 12-13^th of August.  Meteors can be seen from 10 August to 15 August.

What time to look:  You can start looking after 10pm.  More meteors are visible in the hours just before dawn.

Where to look:  Anywhere in the sky is good.  Once Perseus is above the horizon, meteors can appear anywhere so just look up.

Observing tip:  If you can, find a place where you can stand in a moon shadow and still see a reasonable expanse of sky.  Perhaps you can use a row of trees, your house, or a building to shadow the Moon.  This trick will help you to see more meteors despite the Moon glare.

Most importantly:  Have fun!

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By Juan Ivaldi, July 18, 2011 8:12 pm

Children and adults alike repeatedly demonstrate their wonder about the Sun, the Moon, and the stars by asking me a wealth of interesting questions at the public astronomy programs where I volunteer my services as an amateur astronomer and sky guide.  It never ceases to amaze me when I see how naturally inquisitive children are and how they love to discover Nature and the Universe.  It makes me think that our fascination with the sky is built into our DNA and is probably as ancient as the human species itself.

During astronomy programs, I interact with many parents who see the discovery moments their children experience and they want to recreate similar moments at home.  Parents often ask me about activities they can do to continue to stimulate their child’s interest.  If you have similar questions, then here are five easy things you can do with the sky to generate family fun time outdoors and feed your child’s innate fascination with Nature.

1)      Make a human sundial.  You will need a sunny day, a piece of chalk if you have a sidewalk or a paved driveway, or a stick (or a rock) if you are in a field.  Have a child stand on the ground straight and tall and face in the direction of their shadow and stand still.  Mark the location they are standing by tracing their feet or place a stone at the center of where they are standing.  Then trace the shadow of their head and shoulders or place a stick to mark one edge of their shadow of their head.  If a sibling or playmate is available, have them do the tracing.  The child can now step away from their spot.  Wait 10-15 minutes and have the child return to their exact position and again face their shadow.  Now retrace their head and shoulders or place a second stick where the new location of their shadow is.  The shadow has moved!  You can repeat this as many times as you like.  This demonstrates the apparent motion of the Sun in the sky.  Of course it is not the Sun which is moving, but the Earth rotating on its axis which makes the shadow change.  This same rotation makes the Sun rise and set each day and is the phenomenon upon which actual sundials are based on.

2)      What goes around the Earth in just over 27 days?  The Moon of course.  This is a great way to talk about the duration of a lunar cycle, the basic phases of the Moon, and why a month is approximately one lunar cycle.  It is no coincidence that the word “month” comes from the word “moon”.  While looking at the Moon with your child you can share the concept that the Moon is illuminated by sunlight just like the Earth is during the day.  As it makes the trip around the Earth, the Moon position and the illumination angle change together.  The Moon’s orbiting motion is why we see the phases change night after night.

3)      Ask your child this question: “What is the Moon made of?”  No, it is not made of cheese!  You’ll see amazement in your child’s face when you pick up some dirt and some rocks at your feet and place this material in your child’s hands.  They will immediately understand that the Earth and the Moon were formed from the same stuff.  The Earth and the Moon are members of the family of the Sun which means they were formed out of the same starting material roughly 4.6 billion years ago.

4)      Find the brightest star in the night sky.  This is a fun question to ask to stimulate scanning the night sky and hunting down a star.  It is also a perfect time to explain that the points of light in the night sky are brilliant fireballs just like our Sun only very much farther away.  Even the brightest stars in the night sky are extremely far away.  The closest star to our Sun is about 25 trillion miles away (a trillion is the same as a million millions).

5)      Locate one constellation and try to see its shape.  This is an excellent way to spend a little time and acquaint yourself and your child with one part of the sky.  Use a map of the night sky to teach the skill of reading a star chart and comparing that to what is actually up there.  Most kids can recognize the constellations of the Big Dipper (Ursa Major) and Orion.  The shapes are distinct and memorable.

To learn what constellations and stars are in the sky tonight, consult any of the online sky charts available for free on the web.  These provide star names, constellations and other information about the sky.  Here is a short list of links:

http://Skymaps.com My personal favorite

http://www.kidsastronomy.com/astroskymap/constellations.htm A simple skymap

http://www.stellarium.org/ Free planetarium software for your computer

Have fun and enjoy the sky!