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December 2005

An early philosopher created a ranking of the sciences, and in his opinion the most worthless science was Astronomy. He said that because he believed that it would be forever impossible to find out what a star was made of because we would never be able to reach one.

Although, he might be right on the fact that indeed we are unable to travel to another star, he was not right in thinking that we never would be able to discover what stars are made of. We know in great detail what stars are made of and how they are able to produce so much energy for such a long time. The secret to this knowledge is spectroscopy. It would be quite beyond the scope of the AstroNews page to explain in great detail what spectroscopy is, but one very simple concept we can use even with the naked eye.

When something gets hot, it will start to glow. For example a piece of metal will start to glow red when you hold it long enough in a flame. Hence the term 'red hot'. But when we make it even hotter, it will start to shine more towards orange and then yellow. It will also look brighter because our eyes are more sensitive to yellow then to red. So we can say that 'yellow hot' is hotter then 'red hot'. Of course, when we keep heating the piece of metal it will melt. The point we would like to make is that the color is a direct indication of temperature. We can use this to classify stars.

When you look at stars you will notice that they do not all have the same color. Some are obviously reddish and others more blue colored. A good collection of stars is the constellation of Orion. Betelgeuse, in the top left corner of the constellation, is a red-colored star. It shines at a temprature of about 6000 degrees Fahrenheit (3600 Kelvin). However, the stars in the belt of Orion are whitish blue, and therefore much hotter. They shine at a dazzling 90,000 Fahrenheit (50,000 Kelvin). Another good example is our sun, neither red nor blue but a nice yellow. The temprature is indeed in between as well: about 11,000 Fahrenheit (6273 Kelvin).

So, although we are not able to travel to the stars, we are able to tell very simply the tempreatures of the stars. The temperature in turn tells again something about the size and weight of a star, and even its age. Pretty amazing indeed, that without traveling or touching we are able to tell so much of objects that are lightyears away!

Special Event

The winter still has to begin in Central Texas, but after December 21 the days will become longer again, and we are "gearing up" towards spring. Of course the coldest months, January and February, are yet to come but it will be pleasant to have more daylight.

A longer night though, does give us some benefits; we do not have to get up terribly early to see something while it is still dark. For example, to see Mercury this month we only have to get up around 6-6:30. If this would have been in the summer, we would have to get up several hours earlier.

Other than Mercury, there is not that much going on in the sky this month. There is a meteor shower on the 13th, the annual Geminid meteor shower, but the Moon will be a spoiler. Because of the light from the Moon will make most shooting stars invisible.

November 2005

The Leonid meteor shower reaches its peak on the morning of the 17th. They seem to originate from the constellation Leo, hence their name. Their true source is the comet Temple-Tuttle, which orbits the Sun about every 33 years.

When a comet gets close to the sun, millions of tiny particles are thrown from the comet, thus creating a big path of these particles. The Earth's orbit happens to pass through a small part of this path. When one of these particles (usually no bigger than a small grain of sand) enters the Earth's atmosphere, it burns up. Because the Leonids are moving at such a high speed in relation to Earth, a number of these meteors leave a long vapor trail.

Comet Temple-Tuttle was nearest the Sun in 1998. The following four years were quite spectacular for viewing the Leonids. People were seeing thousands of meteors within an hour's time. This year we should expect anywhere from 15 to 100 meteors per hour, which is still quite impressive. However, the Full Moon just two days earlier will be a bit of a hindrance.

Talking about the comet Temple-Tuttle:


You might remember that this comet was in the news earlier this year when NASA slammed a large metal "bullet" into its surface on July 4th. The mission was called Deep Impact and was a huge success. NASA has learned a great deal about comets from the mission. You can learn more about Deep Impact by visiting the official Deep Impact website.

Special Event



For some reason everything to do with Mars is always hyped. Probably this is because Mars shines so obviously red in the sky. Mars was known as the God of war, undoubtedly for its 'blood' color. Well, Mars is red and this is indeed clearly visible to the naked eye this month, but it certainly is not as red as blood!

Unfortunately, because of all this hype observing Mars for the first time is often a big disappointment. These days we are dazzled by amazing Hubble pictures and also close up images of Mars from all the orbiters around this planet. By seeing these images, people assume that when they look through a telescope, they will see something similarly spectacular. Then, when they see a brownish-reddish blurry picture with some white spots and some lighter and darker areas, people are disappointed.

Mars as seen through a telescope
Mars as seen through a telescope. Image taken from Astronomy Picture of the day 26 August 2003.

The trick is to know what to expect when you look through a telescope. Just the very fact you can see some surface features at all with even a very small telescope, is quite spectacular. The image to the left gives you a very good idea how Mars would look like through a telescope.

As you can see the image is wobbling and quite blurry. This is because of the movement of air in the atmosphere. The worse this is, the worse the seeing is in a telescope. You can see several features of Mars. You can see the south polar cap and darker and lighter areas. With a good map of Mars you will be able even to name some of the features visible!

The trick is to have patience when observing. There are times when all of the sudden the seeing is perfect, and for that short time you are able to see much more detail. It also takes (a lot of) practice. Good luck observing Mars this month, and if you have something to share about your experience, please let us know and we may publish it on next month's Astro News.

October 2005

As you know, the Earth rotates around the Sun just like all the other planets of our Solar System. But the further a planet is away from the sun, the lower it's velocity. Also, if a planet is further away from the Sun, the circle it describes is larger. Therefore the further a planet is from the Sun, the longer it takes to complete one circle around the Sun. Taken the fact that the Earth is closer to the Sun then Mars, we are rotating faster and every two years we pass Mars. This point of closest approach is called 'opposition'. For the Earth and Mars this happens approximately once every two years.

But the story does not end there. Both the orbit of the Earth and Mars are not perfect circles: they are ellipses (elongated circles). Mars has an orbit much more elongated than the Earth, and in comparison we can say that the orbit of the Earth is circular. Due to the eliptical nature of especially Mars' orbit, the point of closest approach is not necessarily at the same day as the opposition. This year, the closest approach is on October 29, the real opposition is not until 8 days later: November 7.

Another effect of the elongated Mars orbit is that not every opposition is as close as the other. Below we have drawn two extremes, one as close as possible and one as far as possible:

A good (close) Mars opposition A poor (far) Mars opposition
Schematic representation of the orbit of the Earth (blue) and Mars (red) around the sun (yellow).


As you can see there can be quite a difference in Mars/Earth oppositions! This year we have a better then average opposition. The coming 6 oppositions will be less then the one from this year; so we have to wait about 13 years for another opposition as good as this one. However, the opposition from 2003 was almost perfect. We would have to wait something like 60,000 years before we will see another approach of Mars that is that close. So, although this years approach is less than the one of 2003, Mars will still be spectacular to observe.


The following is a repeat from last month's Astro News

We have received many questions about the Mars oppositions in October. These questions mostly relate to an email that has been going around making some eyebrow raising statements. Interestingly enough the email is a mix of almost correct statements and one very unfortunate typo. First of all the letter states that Mars will be at its closest at August 27, and this is the closest that Mars will be in something like 60,000 years. What is being referred to is the Mars opposition from 2003, not 2005. Indeed in 2003 we had a very close opposition for Earth and Mars. This year it still will be above average, but not as good as in 2003. So that is the first mistake.

The second mistake in the letter is due to a very unfortunate typo... These two sentences appear in the letter:

  • At 52x magnification.
  • Mars will be as big as the Moon!

The unfortunate thing is that these two sentences were originally ONE sentence. Indeed at the proper magnification Mars will be as big as the Moon. Needless to say, Mars will *not* be as big as the Moon in our sky. So if you receive this email from family or friends you now know what to tell them!

September 2005

Of course you know that the sun rises in the East and sets in the West, but not only sun does that also the moon rises in the East and sets in the west. In addition the planets do exactly the same! Almost all the objects from our solar system make the same apparent path through the sky: from East to West. The reason for this is that our solar system is flat, all the planets rotate in a disk (or a plane) around the sun and all the planets rotate in the same direction.

A representation of the ecliptic and the apparent path of the sun

A representation of the ecliptic
and the apparent path of the sun

The path that the planets and the moon follow is called the ecliptic. The moon nearly follows this path as well, but strays above and below it in the time (almost a month) it takes to go around the earth once. During this time, the moon crosses the ecliptic twice. From the Greek word for ‘failure to show up’ an eclipse happens when the sun, moon and earth form a straight line as the moon crosses the ecliptic. If the order of the line is sun-moon-earth, we have an eclipse of the sun – or solar eclipse. This is when the moon’s shadow is on the earth. If the sun-earth-moon line up, we have a lunar eclipse – the earth’s shadow is cast onto the moon. With either of these situations, a full or partial shadow is present. If the alignment is exact, then we have a total eclipse.

As you may know, the earth is tilted on its axis (about 23.5°) in relation to its path around the sun. The angle of tilt can be seen on most globe atlases of earth. This tilt defines how big the Arctic and Antarctic Circle is at each end of our planet. Each region is tilted away from the sun for six months and tilted toward it the following six months. This, of course, is the reason each polar region has half year of light (i.e. the ‘Land of the Midnight Sun’) and a half year of darkness. The autumnal equinox marks the first day the sun shines at the South Pole, and the beginning of six months of darkness at the North Pole.


We have received many questions about the Mars opposition in October. These questions mostly relate to an email that has been going around making some eyebrow raising statements. Interestingly enough the email is a mix of almost correct statements and one very unfortunate typo. First of all the letter states that Mars will be at its closest at August 27, and this is the closest that Mars will be in something like 60,000 years. What is being referred to is the Mars opposition from 2003, not 2005. Indeed in 2003 we had a very close opposition for Earth and Mars. This year it still will be above average, but not as good as in 2003. So that is the first mistake.

The second mistake in the letter is due to a very unfortunate typo... These two sentences appear in the letter:

  • At 52x magnification.
  • Mars will be as big as the Moon!

The unfortunate thing is that these two sentences were originally ONE sentence. Indeed at the proper magnification Mars will be as big as the Moon. Needless to say, Mars will *not* be as big as the Moon in our sky. So if you receive this email from family or friends you now know what to tell them!

Special Event

This month's special events are related: the Autumnal Equinox and the Harvest Moon.

The Autumnal equinox marks the beginning of fall in central Texas and the rest of the northern hemisphere. At this point we can officially begin anticipating cooler weather :-). On both equinoxes (there is one for spring as well) night and day are equal. In fact, the word equinox comes from Latin, meaning ‘equal night.’ After the autumnal equinox, nights become longer and days become shorter all the way until the winter solstice in December. Equivalently, days become longer with the advent of the Vernal (spring) equinox. These events are opposite for the southern hemisphere.

The Harvest Moon is just the name we give to the full moon closest to the autumnal equinox. As with every full moon, the harvest moon rises right at sunset. During the year – on average – the moon rises 50 minutes later each evening. The harvest moon rises only about 25 minutes earlier each night for several nights, thus keeping after twilight darkness at bay for at least an extra week while the moon is fat. This was important to farmers gathering crops in the many centuries before electricity. These days it helps us forget – for a little while – that the days are truly getting shorter. The reason the Harvest Moon rises just 25 minutes later each night is because the moon’s path is closest to the ecliptic (see the Did You Know section below) at this time of year.

August 2005

The first true visionary of space travel was undoubtedly Jules Verne (1828-1905), but the first person to actually tackle the science of this subject was Konstatin Tsiolkovsky. He was born in Russia in 1857 and was home schooled until age 16. He was not accepted at the local grade school, because he was deaf. Despite this, he became intrigued in rocketry at a very young age.

Konstatin Tsiolkovsky  

Playing with a balloon when he was about 12 years old, he understood why a balloon flies away when released. When a balloon is at rest, the air inside will press equally to all sides and the balloon will not move. But when there is an opening the air on the opposite side has no opposite counterpart anymore and will propel the balloon forward. He also realized that this would work in a vacuum. Actually, it would work better in vacuum because there is no air resistance to hold back the balloon! So, unlike most people think, the balloon does not propel itself because of the air that rushes out of the balloon.

He further theorized, that if you would be able to keep the air somehow in the balloon under high pressure, the balloon would keep flying. This was how he came upon the idea of a rocket engine powered by liquid fuel.

At age 16, his dad sent him to High School and University. Tsiolkovsky, eventually became a math teacher, but in his spare time he spent most of his time thinking and writing about rocketry. This was of course not understood by his surrounding and he was often mocked because of his “crazy” ideas.

Being a math teacher, he also developed formulas that describe rockets and rocket engines. He even figured out that you would need a multi stage rocket to reach the moon. The basic equation for rocket propulsion, the Tsiolkovsky rocket equation, is named after him.

When he was 60 years old, the Bolshevik Revolution took place. Unlike the Tsar, the Soviets did realize his brilliance and he became a member of the Academy of Science. Between 1925 and 1932, 60 of his papers were published.

Tsiolkovsky envisioned it all: satellites, people in space, manned space stations, manned missions to the Moon and Mars and populated space colonies in high Earth orbits. On his grave stone are his most famous words: “The Earth is the cradle of humanity, but men cannot stay in their cradle forever”. Tsiolkovsky died in 1935.

Special Event

Happy Birthday Astro News!
This month's issue is exactly one year after we started with writing the Astro news page. We have received many positive reactions, and we sure have a lot of fun writing these pages. We sincerely hope that there will be many more Astro News pages to come!

Every two years when Mars and Earth are at their closest point, the time is ideal to launch a spacecraft to Mars. During that time it takes the least amount of energy to travel to Mars, and for the past years NASA has used this opportunity every time. This time MRO will be launched. MRO stands for Mars Reconnaissance Orbiter, by far the largest spacecraft ever sent to the red planet. This satellite will not land on the surface of Mars, but it will do its research from above the Martian atmosphere. It will search for water, and will be able to take high resolution images. If all goes well, we will sure learn a lot more about the red planet. The official MRO website you can find here.

On August 12 we experience our annual Perseid Meteor shower. Although the moon is about half, it will set before most of the activity will take place leaving us with a perfect dark sky. There are also some predictions that this year we might see some extra activity lasting a couple of hours. These predictions are getting better each year so that is something to look out for. This peak is expected around 4 a.m. on the morning of August 12th.

In last year's astro news we detailed exactly how to observe this meteor shower, so instead of repeating ourselves, you can look it up using the pulldown above the calendar to go back to last year's news.

July 2005

Astronomers of all kinds like to throw a party. This party doesn’t involve bright lights or a bunch of noise. This party requires some telescopes (the more, the merrier), a group of people who appreciate the stars and planets and a nice, quiet dark sky (the darker, the better).

This kind of party is called a Star Party. People from all walks of life and all ages are welcome at this party. People who know just a little or nothing about astronomy are very welcome here. People who know a lot about astronomy are at the Star Party and are very willing to teach others about the fun and science of astronomy.

FOTAP Star Bubble

The Austin Astronomical Society and St. Stephen’s Episcopal School is throwing just such a party during the month of July. Please mark your calendar for July 16, a Saturday, for "Austin Under the Stars" at St. Stephen’s School.

The Friends of the Austin Planetarium will be there with our new StarBubble. The StarBubble is a portable planetarium that can hold about 20 people. It will be set up inside a comfortable, air-conditioned room. Every half hour you can catch a free presentation. This will give you an idea of how wonderful it is to experience a planetarium. We will have koozies and mugs available. Come by and find out how you can get one! We’ll be glad to talk to you about what you can do to help bring a planetarium to Austin.

Please note that due to inclement weather this event has been rescheduled till August 13! Maybe Mother Nature will be kinder next month – please join us at St. Stephen’s on August 13, 2005!

Special Event

Two very important items of special interest occur this month. They both reflect the human pursuit of science and our presence in space.

Deep Impact Mission logo

On the evening of July 3rd (actually the morning of July 4th), Project Deep Impact will reach its destination with a visual display worthy of a Fourth of July fireworks celebration. At about 12:52 a.m. Austin time (so that’s a little after midnight) a projectile will impact on the surface of a comet. You might even be able to see the flash at impact using your own telescope. Comet 9P/Temple 1 will become the focus of new discoveries as we look at the effects of smashing an 820 pound bullet into a large, dirty snowball at a speed of 23,000 miles per hour! This will not destroy the comet at all, but by observing the comet before and after the impact we will learn a tremendous amount about what a comet is made of. For more information on this spectacular mission please visit NASA's Deep Impact website. Also, the Griffith Observatory has a nice page for finding the comet before impact happens.

The other notable event for July is the return to flight of the Space Shuttle. The shuttle has undergone some major upgrades and improvements since the Columbia disaster on February 1, 2003. NASA is viewing the next two flights of the shuttle as test flights. The shuttle Discovery is already sitting on the launch pad at the Kennedy Space Center in Florida ready for a launch. The launch was set for July 13th, but delayed until the 26th. Our hopes and prayers go out to the flight crew of STS-114 and NASA. Please visit the Return to Flight website to find out more about this important mission.