Image via Wikipedia

Solar Eclipse

When a bright day suddenly turned into night because the sun became completely dark is called total solar eclipse. In total solar eclipse, the moon completely blocks the view of the sun. How can the moon completely block the view of the sun when the sun is very much bigger? The sun may be very big, but it is very far from Earth. The moon is small but it is nearer to Earth. So, the sun and the moon appear to be of almost the same size in the sky. During a total solar eclipse, the sky becomes dark and some stars can be seen. The darkness may last for only a few minutes. As the moon moves on, the sun becomes bright again. A total solar eclipse can be seen only in places which lie in the path where the moon’s shadow passes across Earth. When the moon blocks only part of the sun, a partial solar eclipse occurs. This does not darken the sky as much as a total solar eclipse does.

Image via Wikipedia

A total solar eclipse is a wonderful sight. Even ancient people were fascinated by it. However, it is not safe to view solar eclipse with your naked eyes whether they are partial or total. Why? Our eyes are sensitive to light. We blink when the light in our homes are too bright. The sun is about 150 million kilometers away from Earth, but its light is so bright it can reach us and enable us to see things around us. During solar eclipse, the moon slowly moves across the sun. if you look at the sun directly, its sudden bright light can damage your eyes. You may become blind forever.

Astronomers learn much about the sun, moon and earth by observing eclipses. They do this by using special filters. Special filters cut the solar light to a safe level. We, too, can observe a solar eclipse. One way is to place a basin with water on the ground. When we look at the water, we can see the image of the moon moving across the sun. Another way is to stand near a tree with plenty of leaves. Sunlight can pass through the spaces between leaves and cast images on the ground. Do not use sunglasses. They do not provide enough protection. To view a solar eclipse without protection, wait until the sun is completely hidden by the moon and only the corona is visible.

Why a solar eclipse occurs during a new moon? We recall that, as the moon revolves around Earth, we see different amounts of its lighted side. The amount of light that we see depends on the position of Earth and the moon in relation to the sun. Earth, moon and sun appear in a straight line during a new moon. At this time, the moon is between the sun and Earth. In this position, the moon blocks sunlight, the sun casts the moon’s shadow on Earth. But solar eclipse does not happen every month when there is a new moon. This is because the moon’s orbit is a little bit tilted to the earth’s orbit around the sun. As a result, the shadow of the moon falls into space and not on earth.

Lunar Eclipse

A lunar eclipse happens when the moon darkens as it passes through Earth’s shadow. A lunar eclipse may be total or partial. In a total lunar eclipse, the entire moon passes through Earth’s shadow. In a partial lunar eclipse, only part of the moon passes through Earth’s shadow. During a lunar eclipse, the moon becomes reddish because, as sunlight passes through Earth’s atmosphere, part of it is bent around Earth and toward the moon. The atmosphere scatters all the colors of light except red. A total lunar eclipse may last for more than one and a half hours. This is because the shadow of earth is much larger than the moon. Unlike a solar eclipse, a lunar eclipse can be seen in most areas on the side of earth where it is night.

Why a lunar eclipse occurs during a full moon? During a new moon, the moon is between the sun and the Earth. Thus, the Earth cannot cast its shadow on the moon. Recall that, during a full moon, the Earth is between the sun and the moon. In this position the Earth can block the light from the sun and cast its shadow on the moon. Therefore, a lunar eclipse can occur only during a full moon. However, an eclipse does not happen every month when there is a full moon. Why? As the moon revolves around the Earth, it may pass above or below the Earth’s shadow. In this way the earth’s shadow does not fall on it. Therefore, no eclipse happens.

Astronomers can predict accurately the occurrences of eclipse. Each year there are at least two solar eclipses and three lunar eclipses that may be seen from different places on Earth.

Image via Wikipedia

Look for a spot on the moon that you can easily find. Observe the moon for a few minutes for several days. Can you find the spot you have chosen? What does this show? The spot you have chosen is a moon landmark. As the moon turns, the landmark stays in the same position. This shows that you are seeing the same side of the moon. When we look at the moon, we always see the same side because, in the same time that the moon revolves around Earth, it rotates only once on its axis.

Why the Moon’s shape seems to change? The moon revolves around Earth as its axis. It takes the moon 29 ½ days to complete one revolution. During this time, it seems to take on different shapes. The moon travels with Earth around the sun. Half of the moon is always lighted by the sun. The light of the moon the shines on Earth is reflected sunlight. As the moon revolves around the earth, it reflects different amounts of sunlight to earth. When the moon is between the sun and earth, we cannot see the lighted side of the moon. What we see is the dark outline of the moon. This is called new moon. A day after the new moon, we see a thin slice of light at the edge of the moon. This is called crescent moon. About a week after the new moon, we see half of the lighted side of the moon. This is called first quarter moon. As the first quarter moon increases in size, it is called gibbous moon. About a week after the first quarter moon, the earth is between the moon and the sun. We can see the whole lighted side of the moon. This is called full moon. The full moon decreases in size until it is again a gibbous moon. About a week after the full moon, we again see half of its lighted part. This is called last quarter moon. After this, the lighted part becomes smaller until we see a crescent moon. Soon the moon becomes invisible, after which another new moon appears.

The moon does not change in shape. It only seems to change in shape because, as it revolves around the Earth, the lighted part that we see increases or decreases in size. As the moon moves from new to full, it is said to be waxing. This means that the lighted part we see increases in size. As the full moon moves to new moon, it is said to be waning. This means that the lighted part we see decreases in size. The apparent changes in the shape of the moon that we see is called phases of the moon. The moon goes through these phases is 29 ½ days.

The moon rises and sets at different times. In the new moon phase, the moon rises with the sun. in days that follow, it rises later than the sun. in the first quarter phase, it rises at noontime and sets at midnight. During the full moon, it rises at the time the sun rises. During the last quarter it rises at midnight and sets at noontime.

Image via Wikipedia

What is the Speed of Light?

The ‘speed of light’, when in an ideal vacuum, space that is totally empty of matter, has been officially clocked at 299,792,458 meters per second.  That’s around 186,000 miles per second.  That’s pretty fast.  It took the Apollo 11 moon landing mission roughly 3 days to reach the moon.  Light travels that distance in 1.3 seconds.

Light takes a little over 8 minutes to reach Earth from our sun.  If the sun went out, it would be 8 minutes before we’d know.

Oddly though, when you start moving out of our solar system, to our nearest neighbour star and beyond out into our galaxy the Milky Way, and then on into the inconceivable vastness of space, the speed of light begins to seem relatively slow.

Light from the next nearest star to our sun, the star Proxima Centauri, takes 4.2 years to get to us.

Pop out to Polaris, the North Star, the star that sailors have used for centuries to navigate their ships around the globe, and light takes around 430 years to reach us.  That means that we are seeing Polaris today, as it was 430 years ago, or when Sir Francis Drake claimed Nova Albion, or modern California, for England.

          You see, the fact that space is infinite brings the stakes up higher. Kind of tips the scales more with the fact that there are billions and billions of galaxies much like ours. So, why couldn’t there be a life like ours somewhere out there. With that being asked, What would they even want with earth? Why would they come here? And if there is a big conspiracy, why would it be a secret?

          These questions have scrambled my brain my whole life. Ever since I could remember. Most of these were brought about, of course, by movies. When I was little girl, I begged and begged my mother to let me stay up and watch Fire In The Sky with her and my older brother. Finally, when she let me, I watched in wonder as story unfolded and these exact questions were asked.

           But it scared me. The violence that was implied in the movie was just too much for me to handle. I wondered for years why they would be so cruel. Why would beings so much more advanced from our own come to Earth just to bully us? And this is what brings doubt in most of our minds that that sort of thing even happens at all. Because the only logical explanation for that question is, they wouldn’t.

           But let’s look at the possibility. Personally I don’t believe in the big bang, as logical as it may seem, I’m a christian woman myself. But if there was a big bang, there could’ve been other planets like ours that were started the exact same way. This may have also began a life much like our own.

            I’m not trying to say they are, and I’m not saying that they’re not. I’m just saying, it’d be nice to know.

Cruithne or 3753 Cruithne is also given other (quite scientific) names like 1983 UH and 1986 TO. Discovered on the 10th of October 1986, Duncan Waldron in Australia, was the man responsible to locate this quasi satellite. A quasi satellite can be very simply described as an object in space that follows the orbit of its planet and is related to this planet when it comes to gravity and the other complexities but is somehow very eccentric in terms of orbiting. Then why is it that after it’s been discovered, we still can’t see it? It wasn’t till 1997 that it was discovered that Cruithne had an orbit way different than that of the Earth. This highly eccentric orbit is better described as a horse shoe kind of orbit.

Here are a few vital stats about Cruithne:

• Diameter: 5 km or 3 miles
• Closest approach to the Earth: 30 times the distance that is between the Earth and the Moon
• Mass: 130,000,000,000,000kg
• Years to complete orbiting around the Earth: 770 years
• Time taken to revolve around sun: About 364 days
• Temperature: 275 Kelvin (About 2 degree Celsius)

So is there any worry of Cruithne and Earth clashing? Looks like not in a long (and I mean LONG) time because the orbit of Cruithne dictates that it follows the Earth in a synchronised way even though scientists claim that Cruithne’s orbit isn’t stable.  

What is this about the eccentric orbit? Well, to the sun, Cruithne is an elliptic orbit (which is similar to that of the Earth) which means that it feels like it follows the Earth. But to the Earth, Cruithne looks like it follows a kidney bean/horse shoe kind of orbit because the orbital speed and distance of Cruithne to the Sun is a lot more different than that of the Earths. Because the Earth revolves around the Sun in 365 days and Cruithne revolves in 364, it means that in the long run, it is going to be the Earth that ends up following Cruithne because Cruithne is quicker than the Earth when it comes to revolutions. The process is then reversed and it will feel like Cruithne is catching up with the Earth and so on and so forth. Eventually (with a bunch of complex science descriptions that I didn’t understand) because of the speed and time difference, the horse shoe orbit and the Earth will pull away from each other. This happens because there are gravitational energy exchanges that occur every single time Cruithne and Earth come very close to each other.

Well, enough of the boring sciency bits, now with the more interesting parts. When can you next see Cruithne? Cruithne’s last series of close interactions with the Earth happened in 1902 which isn’t really that long back. The next time there will be a set of close meetings will be in the July of 2292 where the Earth greets Cruithne at a (very tiny) 12.5 million km. Cruithne again meets Earth in what seems like every 380 to 390 years. Shame we can never see it, eh?

To spot them today, stand in the shade and look due east of the sun’s position. Once you spot the crescent moon, look a few thumb-widths around it for Venus. Don’t use binoculars or a telescope to view them during the daytime, as you may accidentally look at the sun. Both will be easier to see once the sun goes down, as they will be among the brightest objects in the sky.

If you live North America you may well also see the International Space Station cross the sky.

As the sun is currently blank with no prominent sun-spots at the time the International Space Station will make it’s transit, it will be very easy to see it’s silhouette. Unfortunately, if you blink you may miss it as the transit may well take less than a few seconds.

You might like my other science articles:

The Perseids Meteor Shower – August 2009

Lunar Eclipse: August 5-6, 2009

Hurricanes, Tropical Storms, Cyclones, and Typhoons

Earthquakes: Causes, Effects and Prediction, Including the Recent California Earthquake

Bubonic Plague: Symptoms, Treatment & Transmission

1.)  Look in the general direction “North”.

It may seem obvious… but messing up here will ruin everything.

2.) Locate the “Big Dipper”.

This constellation really jumps out more than anything in the night sky.  It looks more like a pot than a ladle, but nevertheless, start by finding it.

3.) Find the edge of it’s ladle.

Look at the two stars that make up the edge of what would be the Big Dipper’s ladel.

]

4.) Trace upwards from those two stars.

Following this line upwards leads you almost straight to the North Star.  If you are still stuck, look for the “Little Dipper”, which looks like it is upside down, pouring into the Big Dipper.  The tip of the Little Dipper’s handle is the North Star

5.) Congratulations! You’ve found it!

Nice job, you could be the next Galileo.  Whatever the reason you looking was, you have found Polaris, and it was easy wasn’t it?  Use this skill wisely my friends…

Image via Wikipedia

As some will already be aware, meteor showers get their names from their ‘radiant’, this is usually a constellation.

From the point of view of the viewer on the ground, the meteors in that particular shower all emanate from that constellation or ‘radiant’.  Hence showers named Perseids (Perseus), Leonids (Leo), Geminids (Gemini) etc.

If in doubt as to whether a meteor is part of a shower on a night a shower is due, and not just ‘background’ meteors, then follow a straight line back from the line traced by the meteor you’ve seen, and see if it comes from its constellation or ‘radiant’.

NEOs (Near Earth Objects) – What threat do they pose? …. http://scienceray.com/astronomy/near-earth-objects-neos-what-threat-do-they-pose/

The Geminids are due to peak on the 14th December 2009 with an average of around 120 meteors visible per hour.  So, if your Leonids were a washout, hopefully you might have more luck with the Geminids.

Remember that the peak meteors per hour quoted for any meteor shower, is the amount over and above the normal amount you might expect to see in the sky at any other time.  These ‘background’ meteors might number anywhere from 3 to 7 per hour. 

If you would like to know a little more about how meteor showers occur, their origins and how best to view them, then I’m sure you’ll enjoy my article at: http://scienceray.com/astronomy/enjoy-the-2009-perseid-meteor-shower/

There are of course many other meteor showers that occur throughout the year, but these are the ones where you’re more likely to be able to see a good number.  If you are interested though, there are many links to meteor shower calendars to be found.

Happy hunting and stay safe and comfortable while you’re viewing.

Not too much to write about this, it is self-explanatory.But for those of you who don’t know what a Meteor Shower is, here’s a quick link

http://en.wikipedia.org/wiki/Meteor_shower

Every August, the Perseid meteor shower takes place. The shower is made up of the remains of the comet Swift-Tuttle,which moves around the sun in an orbit. The shower is named Perseid because it radiates from the constellation Perseus. This event will take place late tonight (Tuesday August 11th and early morning of Wednesday, so between 11:30 and 4 am)

I live in Southern California, so here is a list of locations for you might want to go to get the best views of the phenomena :

Griffith Park (not the Observatory)
http://www.griffithobs.org/

Del Cerro Park (the BEST location, if itsnt foggy or cloudy )
http://www.palosverdes.com/rpv/recreationparks/DelCerro/index.cfm

Fred Hesse Park
http://www.palosverdes.com/rpv/recreationparks/FredHesseJrCommunity/index.cfm

Image via Wikipedia

The Perseid meteor shower actually occurs due to the Earth’s orbit around the Sun passing through debris left behind by the comet Swift-Tuttle.  In effect the Earth is passing through the remnants of the tail of that long passed comet.

So why do the meteors or meteoroids appear to emanate from Perseus?  Well the easiest way to explain this, is to imagine the Earth as if it were a car driving through snow fall.  To the observer on the ground (or in the car), although the snow might be falling very slowly downward, it appears to the observer passing through the fall as though it is coming toward the windscreen (or Earth), and always from the same direction.  Hence the Perseids appearing to originate from one area of the night sky.

What causes the ‘shooting stars’?  Well, each grain of grit or dust left over from the tail of the comet might be travelling at anything up to 45 miles per second when it hits our atmosphere.  This very high velocity causes friction which in turn gives rise to heat and light.  The heat is usually enough that the debris or dust disintegrates very quickly, often within less than a second, but the light is also bright enough that we see a very fast streak of light in the night sky, ending when the meteor has burned up.  Any meteor that makes it to the ground is called a meteorite.  I’ve been lucky enough once or twice to watch shooting stars that have actually broken up into smaller pieces as they disintegrate, which really does give you an amazing show.

The Perseids meteor shower can produce upward of 50 meteors or shooting stars per hour, sometimes peaking at 70 or so.  This is over and above what one might expect to see on any normal night, which is termed the ‘background’ rate.  On any given night, regardless of meteor ‘showers’, one might expect to observe a background rate of between 3 and 7 meteors per hour burning up in our atmosphere.

So, find a good spot, out in the country if you can, well away from the light pollution that is caused by the street and house lights in our towns.  That doesn’t mean that you won’t see anything in town, it’s just likely that you’ll see much more if you find somewhere without the light pollution.  The best time to view the Perseids, or any other meteor shower for that matter, is somewhere between 10pm and dawn, so take a flask of something warm with you.  Lay on a blanket or if you have a sun lounger you can take along, all the better.  Viewing from a reclined position will save a lot of neck ache and make for a much more comfortable night.

I do hope you enjoy the show, and that you have more luck than I’ve had so far this year as it’s been cloudy on each night I’ve tried to watch.  Oh well, I’ll look forward to the Geminids again in December, maybe I’ll get a better view of those.