Jupiter and Venus

Figure Obtained from Astronomy Picture of the Day

               This picture was obtained from Astronomy Picture of the Day, it was posted on March 18^th 2012.  The two very bright objects that are shown in the image are Venus and Jupiter. Venus is known as the sister planet to Earth. It is closer to the sun then Earth but it is very close in size and composition. Venus is one of the four rocky planets that are located in our solar system. It appears to be very bright in the night sky this time of year because of its proximity to Earth as well as the very thick clouds that blanket the whole planet. As mentioned above the other bright object is Jupiter. Jupiter is the largest planet in our solar system and has a large number of moons. Four of these moons are very large one being larger than the planet Mercury. These moons are known as the Galilean moons. I was able to observe Jupiter last week when it was higher in the sky and at dusk and from a telescope one could see the four moons. Jupiter is not like Earth and Venus in composition and in size. It is one of the four outer planets that are normally called the Gas Giants. This is because they have very large layers of gas and supercritical components and a very dense and small core. The core is more massive than Earth but it is smaller is size.  It is interesting that no matter where you are on Earth at this time of year on a clear night everyone on Earth can see these two objects with the naked eye. Anyone on the planet with a clear western horizon at sunset could see them. If you missed seeing these objects in the night sky the APOD site says that you will get another chance next may to see these objects close together.   

The Active Sun

Figure obtained from: Astronomy Picture of the Day

           The picture above was taken from astronomy picture of the day. It was posted on March 15^th 2012. The pictures are of the gamma-ray sky and some recent activity that has occurred very close to home.  When one takes a picture of the sky in the gamma ray region of the electromagnetic spectrum usually the most exotic and energetic of astrophysical environments can be observed.  An example would be like the active galaxies such as quasars. These are very small galaxies that look like stars and they are powered by supermassive black holes. Another example that is shown above would be a dense pulsar. A pulsar is a rapidly rotation neutron star that emits regular radio waves at rates around one thousand pulses per second.  One can see that in the bottom picture the Sun lights up part of the gamma ray sky. This is due to a massive solar flare that occurred on March 7^th. This is just one of the recent solar eruptions that have occurred.  This solar flare had energies up to 1 billion times the energy of visible light photons. This is amazing because on most other days the Sun would not show up in these gamma ray images because they do not have the massive amounts of energy.  The Sun will most likely shine again in the gamma ray sky in the not so distinct future because we are approaching a sunspot maximum. This is the period of time when the Sun will increase in activity. This increase in activity may have effects on Earth. One of the main effects would be auroras. As well the charged particles that are coming off of the Sun during this active time may disrupt radio and electrical transmissions. It will be neat to follow this increase in the Sun’s activity! 

Holy Moon!

Figure Obtained from Astronomy Picture of the Day

          The picture above was obtained from Astronomy Picture of the Day. The picture was posted on March 10^th 2012.  I chose to write about this picture because I was astonished by the size of the moon in this picture. It was taken on March 7^th in California; the building that is in the forefront of the picture is the Lick Observatory that is perched on a mountains 4200 foot summit. One notices many features of the moon in this picture. One of the main features is the color of the moon, which is not the silver color that we are used to seeing. This is caused because the moon reflects the Sun’s light. This is because the moon does not produce its own light and thus reflects the light from the sun. When the sun is just rising like in the picture above the sunlight is filtered by the atmosphere. This causes the red light that has longer wavelengths to move through the atmosphere hence giving the moon its orange glow. The atmosphere also gives the moons outline its ragged rim.  This has to do with atmospheric refraction that is occurring.  One can also notice a number of the moon’s lunar maria. These are the dark a regions of the moon that is shown in the picture above, these maria make up the “Man in the Moon”. The reason that the maria are different from the rest of the surface is because they are composed (basaltic) of a different material. They are basaltic plains that were formed by ancient lava flows. They are less reflective than the light regions “lunar highlands” as a result of their iron rich composition.  The maria cover about 16 percent of the lunar surface. From this dramatic picture one can see many aspect of the moon that are less distinguishable if taken when it appears further away. 

Spiral Galaxy ESO 510-13

Figure Obtained from: Astronomy Picture of the Day

          The picture above was obtained but Astronomy Picture of the Day. It was posted on March 4^th 2012.  This shows a spiral galaxy edge on and it has a distinctive warped appearance. A galaxy is a collection of millions, billions, or even trillions of stars gas and dust that are gravitational bound. The material rotates around a center.  The center of the galaxy is the location of a supermassive black hole. Like our Milky Way Galaxy this galaxy is spiral. As well from the edge on view one can see the dimensions of the galaxy. The length of the galaxy is enormous compared to the thickness of the galaxy.  The dark bands that are shown in the figure above are where the gas and dust as well as some stars are located.  As well there is a large part of the galaxy that we are not able to see. This is the large amount of dark matter that is located at the edge of the visible galaxy and it expands out to large distances.  This dark matter is what allows deviations in Kepler’s third law. If the orbit of the stars around the galactic center follows Kepler’s third law then the further the star is away from the center the slower it orbits of the stars around the center are. However, this is not true for galaxies. The speed of rotation increases up until a certain point and then it stays relatively constant as you move away from the galactic centers. This change is caused by the sheer amount of dark matter that surrounds the galaxy. But why is this galaxy warped? It is also important to note that the disks of galaxies are thin and flat but not solid. It is thought that some wraps result from interactions or collisions between galaxies.  It however, is not completely known, and it is also thought that our galaxy is thought to have a small warp.