Figure Obtained from Astronomy Picture of the Day

The picture from Astronomy picture of the day that I chose to write about this week is from April 18^th 2010 which is my birthday. The picture that was posted is above and is a picture of the Sun.  The picture of the Sun is most likely taken in the x-ray because one can see the sun in great detail. One can see from the picture that the picture is taken when the Sun is active.  The large eruption that can be seen in the top of the picture is one of the largest eruptive prominences that have ever been seen.  The eruption was captured in movie form by NASA’s twin Sun-orbiting STEREO satellites. A prominence is a large and bright feature of the sun and is often looped in shape. This means that it looks like it comes out of the sun and goes back into the sun. Prominences are anchored to the Sun’s “surface” in the photosphere and extend outwards. The prominences can extend into the Sun’s corona. If the prominence beak apart it gives rise to a coronal mass ejections. When a coronal mass ejection occurs it expels hot gas into the Solar System. The size of this prominence that is pictured above can fit many Earth into the loop. The gas that is released is made up of charged particles and they make it to Earth in approximately four days. When the particles get to Earth they can get trapped in the magnetic field or be deflected off. During high activity from the sun, the particles that are released can cause power outages on Earth and other factors. One of the phenomenon that some people on Earth are lucky to see is the Auroras. For a recap on what they Auroras are and how they are formed one can read the first post in my blog.  Along with the large prominence that is located on the top of the picture there are smaller eruptions that also so how active the sun can be. 

Information obtained from:

http://apod.nasa.gov/apod/ap100418.html 

The Witch Head Nebula

Picture obtained from: Astronomy Picture of the Day  

        This week I will take a closer look at the photograph that was posted on Astronomy Picture of the Day. This picture was posted on January 17^th. One can see that this is a nebula and it is located in the constellation Orion. It is called the Witch Head nebula because many people are able to see the silhouette of a witches face. I however, cannot see the head. This nebula is close to 1000 light years away and has a blue appearance for two reasons. One of the reasons is because of Rigel’s blue color. The other reason is because the dust grains reflect blue light. The nebula is made of large amounts or gas and dust and may collapse to form another star or star system. The clouds can collapse under the influence of its own gravitational attraction. This process is known as Jeans instability. The cloud can reach this unstable point in a number of different ways. Stars that are nearby can cause winds that can compress gas and dust in the nebula, a shockwave from a supernova can cause the nebula to collapses and finally the collapse can occur when clouds collided together. When the nebula collapses a star forms. By studying nebulae like this one may be able to better understand the process of star formation.

Aurora

Figure obtained from:Astronomy Picture of the Day

                                                                                                                                                                  I will be writing a blog each week and the topics will be based on a new picture each week. I will pick the picture from the site Astronomy Picture of the Day. The picture that is shown above is a picture that was captured of the Aurora that was observed over Norway.  Aurora’s are a phenomenon that occurs because of Earth’s magnetic field. The Sun is very active and releases charged particles continuously which are called the solar winds. The Sun also can eject large amounts of charge particles by solar flares, and coronal mass ejections to name a few. When these charged particles are released from the Sun it takes two to four days to reach the Earth. Most of the charged particles are defected by the magnetosphere and do not harm Earth. However, there are some that get through and get caught in the Van Allen belt. Most of the charged particles that are caught in the belt are concentrated at the poles. When these charged particles are escaping they interact with gases in the area of the poles and this is what causes the Aurora or the Northern or Southern Lights. The Aurora’s are normally above the atmosphere and are in ring around the poles. However, the distinct ring is not seen in this picture. There is a correlation between the Sun activity and Aurora activity. Sun spots on the Sun are a way to see how active the sun is. The sun follows an approximately 11 year cycle, and we are approaching an active year for sun spots. This means that there may be more chances to see the magnificent views of these Aurora.