APOD 2.1

Mars currently has two moons orbiting it at the moment, Phobos and Deimos. They aren't particularly large but they are still caught in the gravitational pull of the red planet. They were originally just small asteroids that got separated from the asteroid presumably by the force of other asteroids hitting into them. Mars may not be a big planet but compared to Phobos, a rather small moon, it is humongous. Because of this it is like a tidal pull and the moon is being pulled into Mars. It is doomed to crash in about 100 million years, Phobos will be no more.

APOD 1.8

Far into the universe a stange thing is happening, two galaxies are combining. NGC 2623 seems to be in the final stages and very soon it could become one. It is about 300 million light years away so it has probably already happen and we have yet to see it but soon the fates of the galaxies will be revealed. The cause of the two colliding is likely a very large black hole that is sucking them into each other. In the picture you can see the thousands of stars and the dust as well as the nebulus clouds. Never have we witnessed such an event and many astronomers are excited to see the outcome.

Chp 5.1-5.3 Outline

5.1

• Optical Telescope- Optical is designed specifically to collect the wavelengths that are visible to human eye.
• Telescope-device designed to collect as much light as possible from some distant source and deliver it to a detector for a detailed study. Depending on the size and power of the telescope one can see several thousand light years into space.
• Refracting Telescope- uses a lense to concentrate and focus the light captured by the telescope.
• Reflecting Telescopes- use mirrors to reflect the image.
• Newtonian and Cassegrain- reflecting telescopes that use secondary mirrors to avoid placing detectors at the prime focus. More complex light paths are also used to allow the use of large or heavy equipment that cannot be plaved near the telescope.

5.2

• All large astronomical telescopes are reflectors because large mirrors are lighter and easier to consturct than large lenses. They also suffer fewer defects and do not need to be replaced or cleaned as often as lenses.
• The collecting area, which is the light gathering power of a telescope, is proportional to the square of the mirror diameter.
• To study the faintest sources of radiation, astronomers must use very large telescopes. They suffer least from the effects of diffraction and are able to better achieve better angular resolution once the blurring effects of Earth's atmosphere are overcome.
• The amount of diffraction is proportional to the wavelength of the radiation under study and inversley proportional to the size of the mirror.

5.3

• Most modern telescopes use charge-coupled devices (CCD's) instead of photographic plates to collect their data.
• The field of view is divided into an array of millions of picels that accumulate an electric charge when light strikes them.
• CCD's are much more sensitive than photographic plates, and are more easily saved into the computer and are much more popular in the astronomical field.
• Photometry may be performed either on a stored image or during the observations, using a specialized detector called a spectrometer, that may be used to analyze the spectrum of the radiation recieved.

APOD 1.7

When images like these are taken it is easy to see the path that stars take. Depending on the time filmed their paths are more or less obvious. This particular picture was from 30, one minute exposures in Cape Cod, Massachusetts. The house and the lighthouse are put in the picture as a frame of reference, so that one can see the scale, and in this particular one it looks as though the stars are orbiting the lighthouse. Several of the stars in the picture are circumpolar, which mean that they never set. These pictures are always interesting to astronomers and they astound other people viewing them.

James Bradley Biography

Connor Boles                                                                                                              Boles 1

Mr. Percival

Astronomy Honors

12 Oct. 2012

James Bradley

            Jams Bradley was a well known astronomer for the discovery the aberration of light, which proved that the Earth moved, which was a key part to the Copernican Revolution because it helped convince the skeptics that Earth was heliocentric. It was the first direct evidence and that is the main reason why he will go down in history as a noted astronomer. He also discovered the nutation of Earth’s axis, and together, they were called the most brilliant and significant of the century.

            Born in March, 1693 in Sherborne, Gloucestershire, England, Bradley had an upper class family. He was the nephew of astronomer James Pound, which later helped him secure a job and helped him in the astronomical field. In 1711 he started his education at Balliol College in Oxford. He continued at his education until in 1718 he was elected to the Royal Society, which was a pivotal point in his career. He continued to excel in his field and gaining more and more prowess and several desired titles.  

            In 1722 he measured the diameter of Venus with his telescope, which he later used to discover the aberration of light. He was attempting to discover stellar parallax of Gamma Draconis when he made his discovery, and he was perplexed at first for the stellar parallax of the star should have shown up immediately. Instead of what was expected there was an annual cyclic motion that the star adopted. His calculations were off by several months with alerted him of another possible cause of the strangeness. Finally, he realized that it was an aberration of light.

            The aberration of light is a phenomenon that produces an apparent motion for many celestial objects that hides their real location. There are many factors that affect the aberration such as where one is on the earth and also their speed and height as well as the velocity and direction of the celestial object. The actual effect is the tilt of the direction that the light is coming from and one’s position. This is what proves that Earth has parallax, a key point in the Copernican Revolution.

            The other discovery that Bradley is known for is the nutation of Earth’s axis. Although the nutation of Earth isn’t a perfect angle such as Euler described it does indeed have the procession. It is able to be seen in the changing tides of Earth’s oceans when the tides move and as Bradley was an avid sailor it definitely helped his career. It is parallel to Earth’s ecliptic, a term used in nutation in obliquity. This discovery is something that changed how all astronomers perceived all events, especially the solar events.

            James Bradley was a key contributor in the astronomical field. He achieved the title of Astronomer Royal and for over 40 years he was an avid contributor to the discoveries in his time period. With such a high position and all that power he has forever made an imprint, and changed how we perceive the universe today.

Observations for the week of 10/1

I was able to see the normal stuff every morning, Jupiter and Venus, but also the bright moon. The moon was at its' full moon phase on Saturday and then every morning at around 630 I was able to see it outside my house. It was in the waning crescent phase on Monday and I was able to see it then with limited cloud interaction. I was also able to see the first magnitude star Regulus when it was close to Venus. Even though Venus has a magnitude of about -4.1 and Regulus has a magnitude of +1.3 and it was difficult to see the star I was still able to see the star. Along with these I have been able to see several first magnitude stars but unable to identify them. I plan on using the astronomy app on my phone to identify them over the weekend when I am not in a rush.s

APOD 1.6

APOD October 1st, 2012: Comet Ison

It is difficult to spot some comets for they are objects that move at incredible speeds and can disappear from view in just hundreds of years, which is very lengthy when concerned with astronomy. This comet could soon grow into one of the brightest visible in the night sky with Earth as the point of view. That is one possibility but another is if the comet gets too close to the sun, and breaks apart into pieces, floating aimlessly through space. Astronomers hope that the first option comes true so that they are able to study the object. It has a magnitude of 18, which is very low, very impressive that the Russian astronomer who discovered it was able to see it. In just 15 months however, the dirty snowball could a completely different object at a very different distance.