Tuesday, November 11, 2014

Light Show From The Lion

There's a light show coming to Salem (and beyond) and it involves the most exciting and elusive lights in the night sky. What are these lights? Hint: They have nothing to do with starlight, even though their nickname is associated with stars. Read on for the answer and a short guide to enjoying these flashing treasures.

Starlight dominates the night sky in the Salem area. When we look up into the night sky and see the Moon, stars, and planets, we can trace almost all the light we see back to a star -- our Sun or one of the thousands of stars we can see with the naked eye. The Moon and planets are reflecting sunlight. The same applies to the man-made satellites we can see in the night sky, like the International Space Station. If you can see a comet, almost all that light is from our star, the Sun. But for drama and excitement, it's hard to beat the light that doesn't depend on starlight. What's that mysterious light? A meteor! Or better yet, METEORS!

There's a stream of meteors headed our (Earth's) way and Salem is a great place to view them because we have dark skies nearby. On the night of Monday, November 17th, (into the morning of November 18th) the Leonid meteor shower will reach its peak. Let's translate that into normal English and figure out how to enjoy the show.
A meteor near the Trifid Nebula.

Let's start with terms.  You might know meteors as "falling stars" or "shooting stars". But they aren't stars. And despite the coincidental timing of hunting season, there's no real shooting involved.

Meteors are glowing bits of dust and rock that have made the mistake of crashing into Earth's atmosphere. They're only glowing because they hit the Earth's outer atmosphere at amazing speeds. As the air is compressed by the particle or rock, the air heats and eventually becomes hot enough to glow. Even after the meteor has passed, the air can still glow until it cools off. That stream of hot, glowing gas is the bright streak of light you see in the sky.

What's the "shower" part? On any clear, moonless night of the year, you can watch the skies and see a few meteors. Usually the meteors are going in random directions and they don't have any relation to one another -- just isolated stuff in space that hits Earth's atmosphere to give you a spontaneous (and short) show. But during a meteor shower, you'll see more meteors and the meteors appear to come from a single point in the sky. Each meteor shower has its own "radiant" or central point in the sky. The Leonid shower has its radiant in the constellation Leo, the lion. You can easily pick out the constellation because the head of the lion looks like a backward question mark in the sky. If you want to see Leo before the shower, just go out on a clear night and look toward the east after midnight. (If you know the two "pointer stars" in the Big Dipper that point to Polaris, you can follow them backward to see the constellation Leo.)

So we know about meteors and meteor showers. But what's the best way to enjoy a shower? The most critical part is having a clear sky -- no clouds and no haze. If the sky is cloudy, the show is over. If it's hazy, you'll see only the brightest meteors. A Full Moon can ruin the show just like haze. But for the 2014 Leonid shower, the timing is great: The Moon won't rise until almost 3 AM, and even then, it'll just be a thin crescent.

If you'll be outside during a mid-November night, you'll need to be prepared for cold weather. If it's clear enough to view meteors, it'll probably be very chilly. So bundle up. Think "blankets", "thermal socks", and "gloves".

There are two wonderful things about viewing meteors: First, your eyes are the best tools for the job. You'll see more meteors with your eyes than you would with a telescope or binoculars. Try to avoid looking at a bright light because your eyes will lose some sensitivity for a while. If you need a light, a dim, red flashlight is the best. (The light should be red. The color of the flashlight isn't important.) Second, the best viewing position is horizontal. That summer lounge chair -- fully reclined -- is the perfect meteor viewing furniture. Try not to fall asleep.

Your viewing location is important. If you can get to a dark location with a low horizon, you'll have the best view. But even in downtown Salem, if you can see stars and constellations, you can see meteors. It's best if you have a good view of the eastern horizon. But you might see some of the best (and longest) meteors of the shower if you look away from the eastern sky. So the horizon view isn't as important as finding a dark location.

So where and when do you look? Most astronomers recommend viewing a meteor shower near the radiant -- in this case, the constellation Leo -- and viewing when the radiant is high in the sky (but before dawn brightens the sky).  If you do that, you'll see the most meteors. And you'll also be in the cold and dark about 4 AM. If you're not ready to make that combination of sacrifices, there's good news. And it involves normal hours (or at least "more normal" hours).

It's true that 4 AM on the morning of November 18th is the time when you'll see the most meteors. But the Earth starts encountering the stream of dust and rocks for a couple of weeks before peak of the shower and we continue seeing those meteors for a couple more weeks. The numbers taper up before the peak and taper down after the peak. So on late evenings a few days before and after the 17th/18th you might catch a few bright, long meteors coming from the eastern part of the sky.

Remember I said that the "most" meteors are seen near the radiant. But many of those meteors are coming right at you. (Don't worry, most burn up and the rest will miss you.) Those "right at you" meteors are unimpressive -- just a short blip in the sky -- because you are looking down (or is it "up") the path of the meteor. The impressive meteors are the ones that miss you by a lot and streak all the way across the sky. Yes, watching the radiant will give you the MOST meteors. Looking away from the radiant, you'll see fewer, but you'll see the best meteors.

Meteor watching can be a fun family sport. Each family member can patrol a separate part of the sky. Some meteors are long enough to hear one person shout (or gasp) but still let another person turn to see part of the streak in the sky. The Leonid meteors tend to be faster than other meteors: They can hit the atmosphere at 45 miles per second. (That's a muzzle velocity of over 237,500 feet per second.)

A meteor shower -- even a good one like the Leonids near its peak -- is more "waiting" than "seeing". The predicted peak of meteor activity for the 2014 Leonid shower is about 15 meteors per hour. That's less than the peak from other years. But meteor showers often surprise astronomers. We could see more or less. It takes patience but the payoff is exciting.

Here's the summary: Find skies with low light pollution, and hopefully a good view to the eastern horizon. Dress for cold weather and relax in a reclining chair or on a blanket. The best time is 2-5 AM on the November 18th. The second best time is anytime during any night until the 30th. The only tools you need are your eyes (and your patience).

There's a lot more interesting information about meteors. See the Salem Skies blog post titled "Meteors". You can also find links to other meteor websites there. And you can leave suggestions, questions, and meteor viewing reports in the Comments section.

Enjoy the lion's light show! Clear skies.

EPILOGUE: The cool weather — into single digits — took some of the fun out of viewing the Leonids. A short viewing session at 10 PM on the 17th showed about 6 meteors from the shower. A much brighter meteor (not a Leonid) went in the opposite direction of the Leonids. Later, at 4 AM on the 18th, I saw 10 more meteors over 45 minutes.

Monday, October 13, 2014

Crescent Sun in the Afternoon

It won't be your average Thursday...unless it's cloudy.

On October 23rd, 2014, the Moon will pass in front of the Sun. Here in Dent County you'll have a pretty good view of the event -- better than most of the world. In fact, most of the world won't see any of the event. And when you consider that the best view of the event is in the northernmost reaches of Canada, you'll be happy to view from the comfort of the Ozarks.

Every month, the Moon swings between the Earth and the Sun. Sometimes it does it twice. In almost all cases, the Moon is above or below the Sun -- like a batter swinging and missing as the baseball goes past him. In a total eclipse -- the best kind -- the Sun, Moon and Earth line up so that the Moon's shadow is cast on circle that can be a few miles to 170 miles wide. In a total eclipse, the whole Sun is blocked by the Moon for a short time. That's a "total eclipse" -- the eclipse version of a "home run".

Unfortunately, the October 23rd eclipse is a "partial eclipse" -- the eclipse equivalent of a "foul tip". The shadow of the Moon will pass just above the North Pole. This means no one on Earth will see a total eclipse. But in any solar eclipse -- partial or total -- large areas of the Earth will see part of the Sun covered by part of the Moon. The northern places in Canada will have the best view of this eclipse -- almost 90% of the Sun covered by the Moon. Here in the Salem area, we'll have to settle for about 40% of the Sun covered by the Moon.

If you want to see the solar eclipse, you need to take some precautions. If you aren't careful, you could permanently damage your eyes. That's a nice way of saying "you could go blind". It's also important for parents to supervise kids so they don't accidentally damage their eyes. The first concern is that people might look directly at the dimmed Sun. Normally, the bright Sun is painful to watch and people look away reflexively. The dimmer Sun might allow people to stare longer even though plenty of damaging light is hitting their eyes. The damage from dimmer sunlight can still cause quick permanent vision problems. The second concern is about magnified views of the Sun through binoculars or a telescope. The lenses of these items collect many times the light that our small eyes gather. That means many times more of the damaging light. Third, don't be fooled by smoked glass or other tools that make the Sun look dimmer to your eyes. The damage to your eyes comes from light that we can't see. Looking at an eclipse through binoculars or a telescope can cause permanent, irreversible blindness in a very short time. BE CAREFUL!

You can avoid the danger of permanent blindness and still view the eclipse. If you have a telescope, you can buy a special astronomy filter for your telescope. You'll need to make sure the filter you buy is the proper size for your telescope. And you need to make sure the filter doesn't fall off the telescope from a bump or wind. If someone is viewing when the filter falls off they could be blinded. Duct tape can do a lot things and it can save your vision by gripping your filter to the telescope.

The safest way to watch any solar eclipse is to view the Sun's image projected, not viewed directly. It's also the least expensive way. "Pinhole projectors" show the Sun's image on a small screen. A simple projector can use just two sheets of paperboard and allow several people to view the image at once. A box version of a pinhole projector gives a single viewer a better view. You can see how to use both of theses styles at the link below . Or you can search for web-pages or videos about "pinhole projector eclipse". If you make a pinhole projector, you can test it on the Sun before the eclipse on any clear day. You might be able to make out some dark smudges on the Sun -- sunspots. A tip about choosing a box for a pinhole projector: The longest box will give you the biggest image of the Sun.

Now for the eclipse itself: From our viewpoint in Salem, October the 23rd will start like any other day. But later in the afternoon, we'll see a change in the Sun. About 4:40 PM the Sun will be in the southwest and little by little the right side of the Sun will be covered by the Moon. Eventually it will look like a bite -- about the same as the Apple logo. It will take over an hour before the maximum coverage of the Sun (about 5:48 PM). For us, the Sun will look like a "chubby crescent". For folks at the best viewing point in the far north reaches of Canada and Russia, the crescent will be very thin because much more of the Sun will be blocked by the Moon. By the time of the maximum eclipse, the Sun will be setting so you'll want to be at a location where the horizon is clear of buildings and trees if you want to follow the eclipse to the maximum amount and beyond.

Anytime from 5:30 PM through sunset, you might see something very interesting in the shadows of trees. The leaves will form the same small "hole" as a pinhole projector so the image of the eclipsed Sun might be projected on the ground. Unfortunately, the Sun will be low in the sky and the shadows from the leaves won't be right under the tree. So you might see the leaf-produced image on a building or piece of cardboard. (See the link below for leaf/eclipse photos.)

After the eclipse reaches the maximum, the Moon will continue passing toward the top of Sun and exposing more and more of the Sun's surface. Our sunset will be at 6:10 PM and the final stages of the eclipse will continue below our horizon until 6:47 PM. Viewers in the western states will see the whole eclipse. The link below shows more details about the exact timing and appearance of the eclipse from St. Louis. That view will be nearly identical to ours.

You might be tempted to take pictures of the eclipse, but be careful. Putting your eye to a viewfinder can cause permanent damages just like viewing through binoculars or a telescope. And if you point a camera with a digital viewfinder, your eyes will be safe but the camera might be damaged. If you use a pinhole projector, you can easily take pictures of the projected image without risking your eyes or your camera. Your pictures will show more details and contrast if you use a box projector. And pictures of the leaf-generated images of the Sun are totally safe.

If you don't want to take the time to view the eclipse in person, you can search for websites that show the eclipse. But a web view of an eclipse isn't the same as seeing the familiar Sun in a very curious shape.

So hopefully you can prepare for this chance to see a partial eclipse. Decide how you want to safely view the eclipse: Pinhole projector, safe telescope or on-line. Find a good location -- a low horizon to the west-southwest. Remember the timing -- starting at 4:40 PM, peak coverage at 5:48 PM, and sunset at 6:10 PM.

Of course, if we have clouds, the show goes on but we won't see it. Whether the sky is clear or cloudy on the afternoon of October 23rd, your preparation for this eclipse will be something you can use in 2017 when you can travel just a few miles to see the most spectacular and treasured event in astronomy: A total solar eclipse on August 17, 2017. Expect to hear a lot more about this event and date over the next three years.


Pinhole projectors: http://www.timeanddate.com/eclipse/make-pinhole-projector.html
Leaf images: https://www.google.com/search?q=eclipse+leaf+projection+partial&tbm=isch
Eclipse details: http://www.timeanddate.com/eclipse/in/usa/st-louis?iso=20141023

EPILOGUE: On the day of the partial solar eclipse, the sky was covered by very dense clouds virtually all day. So nearly the whole event was clouded. However, in the middle of the invisible eclipse, the clouds thinned just enough for one decent photo showing that the eclipse was real. The inset in the photo shows the Moon on the upper right covering part of the Sun.



Wednesday, October 1, 2014

Red Moon at Dawn

If you are an early riser, be sure to circle "October 8" on your 2014 calendar. And set your alarm to wake you VERY early that morning. You might be able to view a colorful eclipse of the Moon in the morning twilight. The sky might share some other excitement, too.

Every so often, the Full Moon will pass through the shadow of the Earth. During most Full Moons, the Moon passes a little above or a little below Earth's shadow in space, and there's no eclipse. But during the upcoming 10/8 lunar eclipse, the Moon will be deep in the darkest part of our shadow for a relatively long one hour. 

You'll want to prepare for the eclipse. Don't worry if you don't have a telescope. You can view the eclipse with your eyes. Binoculars can make the view much better. And, of course, any size telescope gives you the best view. Don't worry about safety -- viewing this eclipse of the Moon is totally safe for your eyes.

Courtesy Victor Rogus, Jadwin, MO, taken 4/15/2014
Because of the timing, you'll need to have a good view to the southwest and west. The best spot will have a view all the way to the horizon in the west-southwest -- you'll get the full view. But just about any place is good for viewing at least part of the eclipse. 

Speaking of timing, you'll want to be outside and ready to view for the best part of the eclipse -- from 4:15 AM through moonset,  after 7 AM. Lunar eclipses are slow-moving events, so a chair or a blanket on the ground might make you more comfortable. There are tips below to help you productively pass the time as the eclipse slowly progresses.

After you wake up, get your gear and settle in at your viewing spot, you should have no trouble seeing the bright Full Moon in the southwest. The brightness of the Moon will make it hard to see most stars or the Milky Way. But starting about quarter after 4 AM you should see the Moon looking a little strange -- like someone took a small bite out of the "top". 

From our view here on Earth, the "bite" on the Moon will continue to grow and by 5:25 AM the whole Moon will be completely inside Earth's shadow. That's the start of the "total lunar eclipse" and for about the next hour, no direct sunlight will reach the Moon. What we see when that happens isn't completely predictable.


Once the Moon is fully eclipsed, the lighting of the Moon depends on our weather around the Earth. If the Earth had no air, the Moon would be totally black -- nearly invisible -- during a lunar eclipse. But our blanket of air bends light, and different colors bend differently. Our blue sky is made of bent sunlight. And our orange or red sunsets are bent sunlight, too. When the Moon is eclipsed, the only sunlight reaching the Moon is bent through our atmosphere. So the eclipsed Moon can be a drab coppery gray or shocking blood color or many other variations, just like the variations in our sunsets. We just don't know before it happens (just like our sunsets). If you're watching, you know as soon as anyone on Earth. You'll be on the scene, watching science news as it happens. And stay alert -- the color and brightness can change over the course of the eclipse.  The totality of the eclipse will continue for 58 minutes. 

The pre-dawn Sun will start to brighten the sky much earlier than the 7:07 AM sunrise. Between the start of totality and the start of twilight, you might catch a few other interesting things in the dark sky during totality:

First, you should have no trouble seeing the bright planet Jupiter in the east. It will be brighter than any of the stars in the sky. You can see four of its moons through a telescope or binoculars. 

Second, you might also see the planet Uranus. Even though it's 1.8 billion miles away and dimmer than most stars, it will be easy to find. It's in a part of the sky with few stars and just to the upper left of the Moon. You might see it during totality with just your eyes, but it'll be much easier with binoculars. If you view it with a telescope, it will look like a very, very blue-green dot -- not bright like a star. 

Third, keep your eyes browsing the sky while the Moon slowly darkens. There will be two moderate meteor showers in progress — the Orionids and Taurids. They're normally tame — 5-15 meteors visible per hour. But sometimes they surprise the viewers with more. The light of the Full Moon would normally hide most of the meteors, but during the darker skies of totality you should catch a few. For meteor viewing, there's nothing better than sharp eyes, so don't worry about the binoculars or a telescope. 

Finally, you might see some satellites drifting overhead. The combination of a dark sky and sunlight from the still hidden Sun makes the drifting satellites stand out in the sky.

The twilight will continue to grow and the Moon will dip toward the horizon. About 6:25 AM, you might notice that the Moon has a bright spot toward the top. That's a sign that the Moon is starting to pass out of Earth's shadow and direct (not bent) sunlight is returning to the Full Moon. 

As more of the Moon is brightens, you might be tempted to quit and get something to eat. But you might miss another rarity. If you can follow the Moon to the horizon AND you can see the horizon to the east, then the eclipsed Moon and the rising Sun will both be visible (in opposite directions) for a few minutes around 7:10 AM. That arrangement is known as a "selenelion". The term is rare so you might be able to use that term to impress or stump an astronomer. The event happens somewhere on Earth during every total lunar eclipse, but only a few people are in the right place with the perfect horizon views of the Sun (due east) and Moon (due west) at the same time. Be careful so you don't accidentally aim your telescope or binoculars at the rising Sun. Otherwise you might seriously damage your eyes.

The show is over when the partially eclipsed and squished-looking Moon finally dips below the horizon around 7:15 AM. Now it's time for some breakfast. Or maybe you're already late for work. 

By the way, if it's cloudy, just go back to bed. Later in October, you might have better luck with the upcoming partial solar eclipse. It's much more conveniently scheduled for the afternoon of October 23rd. And we'll be treated to two more lunar eclipses in 2015.

Moon moving into Earth's shado

EPILOGUE [12-2-2014]: The clouds were cruel to people near Salem who hoped to enjoy the eclipse. Just after the Moon was darkening, clouds rolled in and stayed until the Moon was completely out of the Earth's shadow.