Crash Course in Optical Telescopes

Refraction

·         Forms an image using a lens

·         Light converges to from an image at the focus or focal point

·         Telescope use an objective lens to form a primary image

·         There are major limitations:

o    The scope has to be long and hold a large/heavy lens

o    Correct shape of the lens is crucial and must be perfect at all times

o    The support of the lens is on the edge of lens and can cause it to sag

o    Lenses suffer from CHROMATIC ABERRATION

§  Refraction is dispersive

§  Chromatic Aberration occurs when the dispersive nature of refraction blurs the original image

·         Would be okay for close objects, but not ideal from distance viewing

Refracting Telescope

Difference between Refracting and Reflecting

Reflecting

·         Uses a series of mirrors to transmit image to a focal point

·         Law of Reflection: Angle of incidence is equal to the angle of reflection

·         Must be CONCAVE mirrors

o    Receives light from range view

·         Telescope uses a primary mirror to form primary image

o    Kind of like WYSIWYG

·         Advantages of using this scope

o    Use of greater diameter which means more light can be collected

§  More light means more vivid, detailed image

o    One perfect reflecting surface

o    Supported anywhere behind the mirror

o    NO Chromatic Aberration

Sirius with and without light dispersion 

Diffraction

·         The bending of light around corners of edges

·         Longer wavelengths of light bend more than shorter wavelengths which results in issues for larger diffracting models

o    Splits light into its component wavelengths (the color spectrum)

o    Causes heavy dispersion

The Milky Way

If you’ve ever looked up at the night sky to see a clouded 
stripe run from one end of your observable horizon to the other, you are looking into the Milky Way galaxy. This spiral formation is your galactic home.

Milky Way Galaxy spiral arms and SMBH

Leading theories about the center of our average galaxy suggest that there exists a supermassive black-hole now named Sagittarius A shaped like a football. From the center we have drawn proof of four separate arms branching outward. The arms of the Milky Way consist of both population one and population two stars. Population one stars are blue in color because they are a younger, cooler formation. These stars are found along the inside of each arm and are a part of open cluster constructions. Population two stars are older and more red shifted in color. These round stars are found in globular clusters and are too hot to form new stars (void of star-forming material).

The Milky Way consists of approximately 200-400 billion stars across a one hundred thousand light-year diameter and six thousand light-year width. Our solar system is believed to be towards the end of a spiral arm that leaves us about 28 thousand light-years away from the center.

You are here Milky Way Galaxy

Pushing Our Bodies and Our Minds

TIME magazine recently published an article on September 15th covering a Twin Study done on the International Space Station (ISS). The study reports the effects of extended periods of space travel on the mind and body of a cosmonaut. Nobody knows these effects greater than astronaut Gennady Padalka, who is briefly described in the article as the new record holder for most days spend away from Earth—878 days over 5 missions!

Gennady Padalka

Check out the full article at http://time.com/4034666/space-body-mind/

Exploring Exoplanets

Exoplanets are planets that are beyond our solar system. Most of the exoplanets NASA is interested in are Earth sized and orbiting a sun-like star in the habitable zone, though the first few confirmed exoplanets were actually Jupiter sized. The habitable zone is the range of distance from the planet to its parent star where life is possible- not too close, and not too far. 

The exoplanets orbiting a sun-like star are the best candidates for becoming definitive planets because the magnetic field of these stars closely resemble the magnetic field of the sun which is strong enough to form a planet. More than 1,000 confirmed exoplanets have been discovered by the Kepler Space Telescope which reached orbit in 2009 and searched for these habitable planets for four years. It discovered these exoplanets by using the transit method which records how much a star's light dims when a planet passes in front of it. This helps determine whether the planet has the exoplanet qualities by showing us how big and how close to its planet star it is. The method used when the first Jupiter sized exoplanets were discovered is the radial velocity technique which detects how much a star "wobbles" when its planet orbits- the closer the planet is to the star, the more the star seems to wobble. Kepler has discovered a variety of planets from gas giants and terrestrial planets, to super-Earths which are planets between the size of Earth and Neptune and are also in the habitable zone. 

Hubble Space Telescope

The Hubble Telescope, named after Edwin Hubble, launched into low-Earth orbit in 1990, is indisputably one of the greatest technological advancements of our time. Without this 2.4 meter mirror working tirelessly every hour of every day, astronomers wouldn't be nearly as far along. Most famous for its ground breaking photo, Hubble Deep Field. Within the first week of its orbit, the telescope was able to reveal over 10,000 galaxies using long exposure through the humble reflector mirror. Today it has helped uncover over 10 billion galaxies in the visible universe as well as aided it providing evidence of the origins of the universe. It also has allowed scientist to find that the universe is ever expanding faster and faster and can determine the exact rate of expansion over a series of digital data it constantly collects. Being that it is the only telescope to be serviced in space by astronauts, the Hubble Space Telescope is one of the greatest assets that our soul-searching species owns. 

Hubble Deep Field

For more information and a better learning experience on the Hubble program as well as some interactive modules visit http://hubblesite.org/.

And It All Started With a Big Bang... BANG!

Well, not certainly. Some scientists would argue this misconception that The Big Bang actually had a big bang. The leading theory is that it was not an explosion, but a very quick expansion. Space and Time are the fabrics of the universe and did not occur in any one place or at any one time, but it happened everywhere all at once. Think of the universe as a big balloon being inflated. Consider the Earth, our galaxy, and the billions of other stars and galaxies to be on the skin of the balloon. If you choose a point on the surface, you'll notice the rest of the rubber stretches further away with every inflating breath.

CMB

 With advanced technology, we have been able to pinpoint--what we think--is an exact period of time and direction in which the creation and formation of our universe took place. This time period is believed to be in between 1.0x10^-43 of a second and 1.0x10^-36 of a second.  Astronomers can measure this time frame through the bread crumbs left behind by the expansion. Namely, the Cosmic Microwave Background (CMB) which is leftover thermal radiation. This radiation is observed in every direction we look as long as we have the right equipment. So where did all of this energy and material come from in such a rapid amount of time? Though we can't be sure, many turn to multiverse theories for answers.

Formation of a Planet

Planets begin forming from clouds of dust and gas that are floating around after the collapse of a molecular cloud called a solar nebula. A few of the more freely floating materials clumped together, form a primitive meteorite called a chondrite. These chondrules then attract other grains from the solar nebula based on magnitude which creates an asteroid. This process continues as the asteroid gets pulled into the Main Belt and begins to take repeated hits by other asteroids which attach to the original asteroid and begin to form a complete planet. This process ultimately takes 500-700 million years to complete.

Multiverse Theories

There are many controversial theories describing the idea of parallel universes.
One theory of multiverse states that somewhere out there is another planet just like Earth, but we are unable to see it because our cosmic sight is limited by the speed of light. We can only see within our Hubble volume which represents our observable universe.

Another leading theory theory is that the space between other possible universes is infinitely expanding, making it impossible to ever reach. There are two sub-theories to this; the first being eternal inflation which states that in this infinitely expanding space, an infinite number of universes is created. The second sub-theory is the Ekpyrotic theory which goes even further and states that two universes collide in multiple locations, creating multiple universes at one time rather than one separate universe within so much space. Think of each universe as a battery and each has a different charge. When the walls of these branes collide, they give and take a bit (or maybe even all) of the energy from the other. This quick transfer of energy and mass is one of the leading theories because many believe this is where the Big Bang came from, a collision.

Two Branes Colliding

An unpopular theory states there are many separate but coexisting universes which affect each other. For example, my decision right now changes the life of myself in a different world. Theorists use this method to try and explain spontaneous quantum behaviors.

In 1995, a man named Edward Witten postulated that different universes existed neatly stacked on separate planes of dimension based on the brane sizes of the universes. He described our's as a brane-3 and we exist in a dimension called "the bulk", and only other brane-3 sized universes can exist in this sub-realm.

Neatly Stacked Branes