Adapting

The atmosphere has terrible effects on our imaging capabilities. When we point our telescopes to the stars, it is often easy to forget that we are looking through the deep collection of gasses that composes our atmosphere. These gasses can distort our images, and even disrupt the accuracy of our data collection.

On a windy night, we often see our images blurred. This effect can also be observed when riding in an airplane, and the plane shakes because of turbulence. Also, when we look at lower objects in the sky, images are likely to be blurred. This is because we are looking through more of the atmosphere, and the gas particles in the atmosphere have more of a chance to disrupt the light on its way to our telescopes. There are many other causes of this image blurring due to the atmosphere. We are able to fix these with a relatively new imaging procedure known as adaptive optics.

Adaptive optics can take many forms. The most obvious way to get around our atmosphere is to literally send telescopes into space, and out of our atmosphere. Telescope such as Hubble, Kepler, and Chandra utilize this form of adaptive optics, and have produced remarkably accurate data. However, this is very expensive to do, and obviously is not feasible for every telescope. This is why astronomers have invented ground-based forms of adaptive optics as well.

The deformable mirror process

One form of ground-based adaptive optics involves something called a deformable mirror. This is exactly as it sounds – a mirror can literally bend to correct for the wave distortions.  A wavefront sensor linked with the telescope measures the distortions of the waves because of the atmosphere, and morphs the deformable mirror to account for this.

Another ground-based adaptive optics method involves creating artificial stars. In this practice of using a “laser guide star,” or LGS, an observatory sends a laser (typically of near-UV wavelengths). The telescope then detects this simulated star in the atmosphere and measures how it is scattered by the atmosphere. Computers are then able to calibrate images of target stars accordingly. This allows for extreme accuracy.

LGS in action

Adaptive optics allows us to collect sharper images, clearer data, and more accurate results. With practices like this, modern astronomy has promise for advancing at an alarming rate.

The Future of Telescopes

Often, it is considered that a bigger telescope makes a better telescope. A larger aperture means a higher light gathering capability and a higher light gathering capability means better objects. However, astronomers and engineers are creating telescopes of the future, where a larger aperture does not necessarily mean a better telescope. A key example of this is the Large Synoptic Survey Telescope, or LSST for short.

LSST, to be housed in El Peñón, Chile, is a telescope designed for sky surveys, or images of wide star fields. It is designed to have a field of view of 3.5 degrees (the entirety of the Sun or the Moon would only take up 1/7 of this entire field of view). This new telescope will allow for this in its design. Instead of consisting of only two mirrors, the LSST will comprise of three mirrors, with the third "tertiary" mirror inside a large whole in the primary mirror. 

This diagram illustrates the light path of LSST

This telescope is designed and intended to collect data for a few specific aspects of modern astronomy. 

• Dark matter and dark energy. This telescope will image deep sky objects in hope of detecting weak gravitational lensing. Gravitational lensing will help observe how much matter is actually in an area, which will help us detect if there is matter present that we cannot physically see, or "dark" matter.
• Mapping the Milky Way.
• Kuiper belt objects. The LSST will help us obtain a better understanding of the objects in our cosmic neighborhood by allowing us to create a better map of our Solar System. 
• Novae and Supernovae. We will be better equipped to observe fleeting events in space, such as star explosions.

LSST creators intend for this telescope to take more images per year than can possibly be processed by humans. This is why they want to make much of LSST's data accessible by the public, in hope that some discoveries will come about this way. Many other telescopes are currently using this practice. 

A Glittered Backdrop of Promise

When searching for exoplanets, our primary interest is in life. "Is this planet habitable?" we often ask. "Is there other life in the Universe?" "Can we make this our own home if we need to?" These questions lead us to the search for a very specific type of exoplanet - Earth-like ones. These questions, and the search for Earth-like planets, have led us to the creation of the Kepler Space Telescope.

Kepler Space Telescope

The Kepler space telescope, or "Kepler," is a modern-day NASA space craft tailored to a certain type of observation - transits. Transits were covered in my post entitled "A Tale of Two Atmospheres." This celestial phenomenon occurs when an object (in this case, a planet) comes between the Earth and the target star. When this happens, we are able to observe a slight dip in the brightness of the light that reaches our eyes, camera, or any other light detector. With this dip in brightness, we are able to determine a lot about the transiting object, including its size and atmosphere.

Kepler is equipped only with a photometer. Wisegeek says "In astronomy, a photometer is used to measure the amount of light contained within stars or other celestial points." Kepler's photometer is very sharp, and can accurately measure the brightnesses of stars with extreme precision. This enables it to survey a field of stars simultaneously, instead of focusing on one target object at a time.

Using Kepler, NASA has been able to locate and confirm the existence of 156 exoplanets, and discover 3,602 planetary candidates. With this data, it is estimated that there are 60 billion habitable exoplanets in the Milky Way Galaxy alone.

A size comparison between a Kepler exoplanet and planets in our solar system.

These numbers alone speak very highly of modern-day astronomical techniques. With the tools currently at our disposal, we are able to discover so much more than we could possibly imagine. As technology advances, we will be able to process more and more data, and learn so much about the Universe we live in.

Oasis in the Desert

Stemming off of last week's post, I would like to discuss something that particularly fascinates me in astronomy: what makes a planet (or moon) habitable for life as we know it.

The most important factor in planet habitability is the presence of water. Water is extremely polar molecule, which allows it to act as a great solvent. I'm not going to get into the chemistry (because, frankly, I don't know it), but water's ability to act as a solvent is vital because it promotes the complex chemical processes that go into the birth of life. Simply put: without water, there is no life.

The presence of water also hints at a few factors that are necessary for life.


One of these is the distance of the world from its host star. There is only a particular distance from each individual star where a planet would be suitable for life. This region is known as the habitable zone, or the goldilocks zone.

In this region, the temperature of the planet is suitable for liquid water to be sustained. As you can see, liquid water is essential for life as we know it.

Another key aspect for life is the type of host star the planet orbits. It takes billions of years for life to form. The more massive the star, the shorter its life span. If you have a planet orbiting a massive star with conditions suitable for the formation of life, the planet may not have enough time to generate life before the star becomes a giant and changes the conditions on the planet. This publication talks about this in more detail.

As you can see, it takes a very complex combination of factors to allow the formation of life. Earth is a very specific gift that we have been given. That is why it is important that we keep researching this field of astronomy and possibly locate planets that may support life. Earth will not last forever. When the time comes that we need to relocate, this field of astronomy may be our saving grace.

A Tale of Two Atmospheres

When on the hunt for exoplanets, there is only one thing on the minds of everyone - Aliens. The search for extrasolar planets is directly related to the pursuit of extraterrestrial life and a second home for our species.

This relatively new field of astronomy has opened up many flabbergasting doors in the realm of planetary astronomy. Many different types of planets have been discovered on our journey. One of the newer types we have come to discover is a category we call super-Earths or mini-Neptunes.

An artist's rendition of Kepler 22b - a famous super-Earth

Needless to say, this category of exoplanets includes all planets with masses in between that of Earth and Neptune. The classification of these planets as super-Earths or mini-Neptunes depends on their atmospheric characteristics. If an exoplanet has a thick atmosphere of primarily helium or hydrogen, it is classified as a mini-Neptune. Conversely, if it has an atmosphere of carbon dioxide or nitrogen, it is a super-Earth.

When searching for extraterrestrial life, we generally look for super-Earths. They are big enough to find using the known methods, and they have atmospheres similar to our host planet's. Life as we know it can only exist on planets with such atmospheres. Mini-Neptunes are simply not suited for life as we know it.

MIT graduate student Björn Benneke has proposed a method for determining the atmosphere of this category of exoplanets, though it is limited to very specific scenarios.

When an exoplanet orbits its host star in a way that allows us to see it cross the star, we are able to observe the light of the star as it goes through the planet's atmosphere. We are then able to divide it into it's component wavelengths and determine what elements are interfering with its travel. These elements interfering with the light's travel are the elements that reside in the exoplanet's atmosphere. Once these are identified, we are then able to identify the exoplanet as a super-Earth or a mini-Neptune.

A representation of a planetary transit of a star

The major problem of this type of exoplanet identification is that it is very limited. We need to be able to see the planet cross in front of its host star. This happens in a very small fraction of the exoplanets we have identified, as it is a geometric rarity.

Snapshots of the Universe

Taking pictures is relatively easy nowadays. Anyone can whip out a smart phone from their pockets and snap a still image of what they're looking at in seconds flat. It's simple.

However, the same can not be said for photographing celestial objects. Simply pointing a telescope at an object in the sky and taking a picture through the eyepiece doesn't yield the colorful landscapes we all know and love. Following this method for astrophotography wouldn't yield very exciting results results.

M17: Swan Nebula - visual light only

This is because we rarely use optical light alone to image objects in the sky. Instead, we filter the light through different wavelengths, take long-exposure images with each filter, and combine the images to form a photograph that truly characterizes the object. This is how professional astrophotography works. 

M17: Swan Nebula - all wavelengths of light

In lab for my astronomy class at school, we went up to SUNY Oneonta's observatory and imaged objects of our choice. This was to help us learn about CCD cameras, the process of astronomical imaging, and how it isn't as simple as the "point and shoot" method. 

The object I chose to image was Neptune, the eighth and furthest planet in our Solar System. I can never get enough of planets. The fact that there are other worlds besides our home planet will always be one of my favorite things about this Universe. The reason I chose Neptune over other planets is pretty simple: There weren't any other planets above my local horizon at the time. Well... That's not entirely true. Uranus was visible at the time, but I never really liked Uranus, so I went with Neptune! 

One of the first steps in astrophotography is taking what is called a "bias frame" 

Bias Frame

Bias frames are just images of the natural static of the camera. We take images of this so that we can subtract this static from the images we take of our desired object. This enables us to have as clear of an image as possible. 

Following this, I pointed the 16-inch Schmidt-Cassegrain telescope to Neptune. With an exposure of roughly ten seconds, I took a series of photographs with various filters. 

Neptune - Red Filter

Neptune - Green Filter

Neptune - Blue Filter

Alone, these photographs don't look like much. It's even hard to distinguish which of these bright dots is Neptune. However, with manipulation and layering via photoshop (something I have yet to learn about), a final image can be created. This is the image my astronomy professor created with my filter images:

As you can see, the blue color of Neptune (the bottom object) is really apparent now that all the images have been combined. I am satisfied with the results, even though the planet just looks like a tiny blue speck. Neptune is far away and incredibly small in astronomical terms, so an image of this quality from an undergraduate astronomy student is very gratifying. 

Grabbing the Sky (The Clark Telescope)

Sometimes looking at the night sky isn't enough. Sometimes we feel such a fervent desire to be up in space with the stars and planets that we simply can't cope with the limitations of our planet...

...And that is when we start to invent.

It's the early 17th century. We finally realize that we have the power to manipulate light. Mirrors and lenses have the capability of reflecting and magnifying images, and we are able to use this capability to our advantage. We can make things appear to be much larger than they actually are with such simple tools. We can see further than we have ever imagined.

Enter: the telescope.

With this tool, we have learned more about our place in the universe than we have with any other piece of equipment.

Hans Lipperhey, a german spectacle maker, is often attributed with the invention of the telescope. However, the first person to point it to the night sky was Galileo Galilei. Galileo realized that the telescope could be used to study the stars, and improved the invention for astronomical purposes.

Galileo's telescope design is what we now refer to as a refracting telescope. This type of telescope uses lenses (typically made of glass) to bend light in a way that makes it appear larger than it actually is.

One famous refracting telescope is the 24" Clark Telescope housed at the historical Lowell Observatory. 

This telescope was created by Alvin Clark in 1896. As Lowell Observatory's website says, "The Clark is one of the largest, most productive telescopes of its era and the first large telescope in the desert southwest of the United States." This telescope has a 24 inch aperture. This means that the opening hole at the top of the telescope has a 24 inch diameter. This is immense for a refracting telescope, considering that the entire 24 inch lens is made of glass. 

The Clark Telescope has been used for some monumental discoveries and research in astronomical history. Percival Lowell, the founder of Lowell Observatory and a renowned astronomer, was the first to conduct research on this telescope. His detailed research on Mars through this telescope helped to popularize the planet, as well as astronomy as a whole. V.M. Slither used the Clark for his seminal galaxy research, in which he detected the radial velocities of galaxies (how fast they are moving away from us). This research eventually led to the idea that the Universe is expanding, as well as the Big Bang Theory. The Clark was also used for mapping the moon. The lunar data obtained by the Clark was used heavily in NASA's Apollo program. 

Since then, the Clark has retired to a placid life of tours and leisurely nighttime viewings. 

Needless to say, the Clark Telescope at the Lowell Observatory is an impressive instrument, as well as a salient piece of astronomical history. Without refracting telescopes like these, our knowledge of the cosmos and our place in it may not be what it is today.