APOD 2.1

The picture above is of the planet Saturn. This picture was obviously not taken from Earth because there is no possible way that we can see all of Saturn, including the side in the shadow since we are in the inside circle and Saturn is in the outer circles of our solar system. This picture was actually taken by a man-made satellite called the Cassini spacecraft which is now in Saturn's orbit and has been taking pictures of Saturn allowing us to attain more knowledge about it.

Around Saturn you can see it's massive rings. These rings are actually millions of billions of rock, sand and ice particles ranging from around the size of sand to rocks as big as houses or even buildings! Some of these rocks are actually from left over pieces from when Saturn was first made. Others come from debris from a meteor or an asteroid hitting Saturn or one of it's moons. The gravitation of Saturn and its moons (up to 60 moons) actually are what keep the rings in place. However, don't think that these rocks are just floating up and down in one place. Theses pieces are actually moving around Saturn at a very high rate which is why the rings seem to blend into one another. You may think that there are only a couple of rings surrounding Saturn, however, there are thousands of rings that circle around Saturn with widths ranging around 30 to 300 feet!

Although you can't see it, all the outer planets have rings surrounding them/ It just seems that Saturn has more rings that are bigger and reflect more light which enable us to see it.

Why is it that all the outer planets have rings and not the inner planets?
In reality, all the planets, yes, including Earth, once had rings around it. So actually Earth did have rings surrounding it once but they were just too unstable to sustain and therefore the pieces or rock and ice we able to pull away from Earth's gravitational pull and fly away.

Unfortunately though, we do have a type of ring surrounding the Earth, rings made of our waste and some debris from things such as our space ships and satellites. This is a problem that we need to start fixing because not only can it possibly hinder future exhibitions in space it may actually affect us people on Earth as well as our planets,

APOD 1.8

Taken in the country of South Africa, this photo shows a detailed picture of our Milky Way, the long belt-like thing at the top of the picture. In this picture, you are also able to see one very bright star-like object in the middle of the sky. However, to many people's surprise, this is not a star, rather it is the planet Venus.

What makes Venus appear so bright, is not because it is emitting that light, but it is actually reflecting the light emitted from the Sun.

There is a term used to express how much light a planet is able to reflect which is the word "albedo". Venus is actually the planet in our solar system that has the highest albedo of up to 70 percent. In other words, the planet Venus absorbs 30 percent of the Sun's light and reflects 70 percent of it.

Some people might come to the conclusion that the reason why Venus is brighter than any other planet is due to the fact that it is the closet planet to Earth. Although it is true that Venus is the closest planet to Earth, what really makes it shine so bright are the clouds that surround the planet. So just like how it is so bright when you look at the snow on a sunny day, the clouds that surround Venus, which is composed of sulfuric acid and other acidic crystals, causes light to easily bounce off and reflect it. This is actually why sometimes the Moon may appear to be duller than Venus, because the Moon only has an albedo of 10 percent due to it's rocky surface and lack of clouds covering it. What makes the Moon appear to be bright is actually how close it is to Earth.

So the next time you look up in the sky, the brightest thing in the sky (which is not always the Moon) is most likely to be the planet Venus.

Observation 1.6

First Quarter

The brightest star in the sky is Venus and it is close to the constellation Scorpius

Date: October 12, 2013
Time: 7:41-7:48 pm

Observations:  The Moon outside today was a little past the first quarter. To the right of the Moon is the planet Venus and the stars around it seem to be the constellation Scorpius. Everyday now, the Moon is getting farther and farther eastward from the planet Venus while Venus is getting closer and closer to the constellation Scorpius.

Observation 1.5

Waxing Crescent

The brightest star to the left of the Moon is the planet Venus

Date: October 7, 2013
Time: 8:22-8:33

Observations: The Moon outside today was a waxing crescent and it was quite bright today. The blurriness of some of the pictures shows that there was a light haze in the sky and I noticed that my camera picked up enough light to outline the whole moon as well. Looking to the left of the Moon I saw a really bright star which turned out to be the planet Venus. This is actually the first time I was able to identify Venus even though I probably saw it every night. I also took some pictures of the sky directly above me, however I wasn't able to identify any of them...I really need to work on my constellation skills. The night was very cool and I could see that the Moon was very close to the horizon, about 3 fists (15 degrees) above it. Also I am still noticing the constellation Orion in the morning sky as it is slowly moving more and more westward.

APOD 1.7

 

Have you ever seen a comet before? If not, then you have a chance to see one around December time. The picture above shows a comet called Comet ISON which was discovered on September 21, 2012.

 

A comet is an ice-like formation which circles the Sun. Made up of water, carbon dioxide and ammonia and methane, it is surrounded by gas and dust which makes that tail-like appearance as it travels through space. Like the Moon, this comet. like all others, will reflect the Sun's light as it comes closer to the Sun and may possibly be brighter than the Moon.

 

This comet is said to possibly have came from the Oort Cloud which is mass formation of ice particles that is around 1 light-year away from the Sun. It is thought that is this the source of many of the comets seen or observed from Earth, however, there is no actual prove of that being the case.

 

Whatever the result of this comet, it is a sight to be seen, as well as meteor showers which are actually debris of comets from the Sun vaporizing bits and pieces of the comet.

 

Be sure to keep track of these astronomical events and just keep looking up!

Astronomy Project: Eudoxus and Callippus

Chelsea Chacko
Percival Period 5
Astronomy

October 10 2013          

Astronomy Project

Eudoxus of Cnidus:

        Being born around the year 390 B.C.E., Eudoxus was a man of great knowledge that led to his famous model of the planets and the basic 5 ideas of space. A man of various capabilities, such as in Math, metaphysics, ethics, and astronomy, Eudoxus began to travel throughout Europe, learning under others who proved their brilliance such as Plato and Archytas. With the influences of his teacher, Eudoxus begins to delve into the subjects and make new discoveries that affect us to this very day.

        During his life, Eudoxus advanced in math as he made the theory of proportions which allowed him to compare irrational numbers and his method of exhaustion which allowed him to find the area of a polygon.

        His major influence in astronomy came from his teacher Archytas. Following his teacher's beliefs of the solar system, Eudoxus, like many others, believed that the sphere was the perfect shape. He made many observations of the stars and sky which he incorporated into the school he made to teach all the subjects he excelled in and became very popular due to that. One of his accomplishments was his creation of the first five basic principles of the celestial world:

1. The Earth is the center of everything.

2. Planets and orbits are all circular.

3. All celestial movement is regular

4. The center of a celestial object when it is moving is also its center.

5. The center of all things is the center of the universe

        Eudoxus not only believed in the homocentric view he also made the first model incorporating his concept of how planets and celestial objects moved called the homocentric sphere system. He pictured his model as the Earth being the inner central sphere encompassed by the 27 spheres which represent the Sun, the Moon and five planets orbiting the Earth. He believed that the outer most sphere (what Eudoxus thought were fixed stars) controlled the rotation of Earth, however, each consecutive sphere has a different rotation around its sphere. Eudoxus saw that in his model of two spheres a figure eight structure called the hippopede appeared. This is where a planet would pass the curve of a sphere. He placed a third sphere to represent the motion of the planet corresponding to the seemingly fixed stars in the sky as the planet went in a retrograde motion seen in many planets. Finally Eudoxus made a sphere to show the daily rotation of the fixed stars. In the end, the homocentric sphere system contained 27 spheres; this revelation became a huge geometrical accomplishment at his time.

        His discovery had influenced the famous Aristotle who took the concept of spheres literally when it is argued that Eudoxus really meant for it to be just a model to represent the paths of the planets.

       His works also influenced Hipparchus, a Greek mathematician, in 2 of his books which included Eudoxus’ measurements of the rising and the setting times of certain constellations which shows the broad range of the effects Eudoxus had on math and astronomy today.

Callippus:

       Born in the year 370 BC, Callippus was a Eudoxus’ student at the school which Eudoxus constructed. During his life, Callippus, with the help of Aristotle, took Eudoxus’ homocentric sphere model and modified the system by adding 7 more spheres which in turn allowed him to accurately measure celestial orbits. Callippus, throughout his life had consulted with Aristotle and worked for him as well, adding on to his experience and knowledge of astronomy.

      Callippus is also known for his precise measurements of the lengths of seasons and his construction of a 76 tropical year cycle compromising 940 solar and lunar months which are used by astronomers to this day.  He also found a more precise measurement of the tropical year of 365.25 days rather than just 365 days which is now accepted world-wide.

      All of Callippus’ findings have and are still being used for accurate measurements of our planets and stars presenting his influence on all the astronomical theories today.

Additional Sources:

1.      http://www.math.tamu.edu/~dallen/history/eudoxus/eudoxus.html

2.      http://www-history.mcs.st-and.ac.uk/Biographies/Eudoxus.html

APOD 1.6

The picture above shows the remains of a star that had exploded. Considering the word "had", this star had exploded around 11 thousand years ago (the time just after the last Ice Age), yet its remains are still in space reminding us of its former presence.

This star is located in the constellation Vela (the Sails).

What causes a star to explode?
Well, a star is composed of elements such as hydrogen and  helium. In the star, there is gravity which pulls in the elements, but are repelled by the heat of the nuclear reaction. The nuclear reaction, however, is continuous, which is why and how our own Sun is here and still ever bright. In the core, there is the fusion of hydrogen into helium into bigger and heavier elements such as iron, which is not as easily fused. Soon (after billions of years, depending on how big the star is), the iron builds up to a point where anymore reaction is impossible and gravity causes the star to cave inwards and explode.

This is what happened to this star.

All these beautiful colors you see in the remains of the star are the gas particles that have flown away from the star. What causes these colors is the reaction of the gas with the interstellar medium.

What is an interstellar medium?
This is basically the stuff in between the stars in space. Yes, there actually is matter up in space. This matter mostly consists of hydrogen and helium and a little bit of dust from some of the nearby stars. This medium is pretty thin, however, with enough of it packed together, some light from stars can be blocked.

Going back to the photo above, the gas decays and reacts with the medium producing these colors.

Observing how Space and its contents work just comes to show the complexity of everything and reminds us of how little we know of everything around us.