Galaxy – Space Age

Tools that Help Us View Our Wonderful Universe- Telescopes

When you look at images of a nearby nebula [1] captured by space telescopes, have you ever wondered what enables you to see such vibrant images of stars with utmost clarity? Telescopes are designed in such a way that they enable us to view distant objects that are light-years away. Most modern telescopes comprise curved mirrors to gather and focus light from the night sky. However, older ones had curved lenses and clear glass that focussed light. These mirrors and lenses are known as optics, which are quite powerful and enable you to see minuscule objects which are millions of miles away. This same principle is used in monoculars and binoculars with the only difference being that they are equipped with much smaller lenses.

Larger mirrors and lenses are used in larger telescopes, this enables light to get concentrated by the shape of optics. This concentrated light is what reaches our eyes when we look into the telescope. Astronomers use mirrors and lenses that are in the right shape to concentrate the light. Any spots, scratches or uneven surfaces on the lens could greatly impair the clarity of the image. It is usually very difficult to make a perfect mirror or lens as it requires a certain level of dedication to achieve the perfect optic stability.

Now that we have understood the basic principle of how we can view images through a telescope, let us now delve into understanding the types of telescopes mainly used in astronomy.

Types of Telescopes

In the world of astronomy and star study, there are two main types of telescopes. They are reflecting telescopes and refracting telescopes.

A refracting telescope predominantly uses a lens to form an image. This is also known as a dioptric telescope which was originally used in spyglasses and later used in long-focus camera lenses. Most refracting telescopes have a lens at the front and a long tube and an eyepiece at the rear. Over the years, Astronomers have experimented with several optics and included even two or three-element lenses that could be added to other optical devices such as binoculars zoom lenses and other types of lenses. The first type of telescope was the Galilean telescope which was used in 1609 and comprises a convergent objective lens and divergent piano concave lens. This telescope provided the foundation for the modern telescopes that we see today.

Modern refracting telescopes use achromatic lenses as they allow shorter focal lengths and resolved chromatic aberration [2] issues. Most observatories use this type of telescope as it is the best suited for viewing objects in the night sky.

A reflecting telescope uses curved mirrors that reflect light to form an image. Isaac Newton invented this telescope, but this suffered from chromatic aberration. Although these telescopes face different types of aberrations, it is widely used in astronomy research due to their design variations that employ extra optical elements to enhance the image. It is widely used in infrared astronomy and is best suited in thermal infrared imaging thanks to its modified mirror surfaces or correcting lens that correct aberrations. Reflecting telescopes are usually used in planetariums and by people who take up star gazing as a hobby.

Hubble Space Telescope

Space telescopes on the other hand are in a whole other league. They are designed with such precision and perfection that they would offer maximum zoom capacity with enhanced clarity. NASA’s Hubble space telescope was the second space telescope launched, with the first being the Orbiting solar observatory, which was launched in the year 1981 to study the Sun. It usually takes nearly a decade to build a space telescope as it demands years of research and intense work with the mirror to provide the best possible resolution ever. Optics experts and astronomers worked for years to construct a 13-inch-thick blank mirror made from ultra-low expansion glass.

When the Hubble was launched in the year 1990, astronomers and star gazers marvelled at the very sight of its images. With no light interference or any other obstacles, the telescope was able to show us amazing images of our universe, which baffled everyone. The whole world was star-struck after having witnessed the marvellous universe in great detail. The Hubble comprises an optical tube assembly along with computer systems and data processing units that helped to calibrate the telescope. It was also fitted with a state-of-the-art integrated camera that enabled to capture of the images in full resolution; this camera is a wide-field planetary camera. The telescope was carried into orbit by the STS-31 space shuttle. In the subsequent missions, NASA had to visit outer space to make a few corrections to the telescope as it faced a few challenges in its initial days. Take a look at some of the images taken by the Hubble space telescope.

James Webb Space Telescope

With advancements in modern science and astronomy, there was a rising demand to view our universe in much more detail. The Hubble telescope was a bit dated and not advanced enough to fuel the curiosity of astronomers. NASA launched the Spitzer Space telescope in 2003, fitted with an infrared array camera, an infrared spectrograph, and a multiband imaging photometer. This telescope enabled astronomers to view a vast nursery of galaxies and nebula with increased precision, thanks to its infrared powered camera. One of the most popular images captured by this telescope is of the Helix Nebula.

Helix Nebula Captured by the Spitzer Space Telescope

After much contemplation and 20 years of research and hard work, NASA launched the James Webb Space Telescope. As of date, this telescope is one of the most powerful space telescopes ever launched. The main intention of launching this telescope is to enable scientists to view further into the depths of space and study exoplanets in detail. This telescope has the ability to view debris disks and infrared bands which are unable to be detected by existing space telescopes such as the Hubble. The James Webb telescope is equipped with a wide range of advanced instruments for easy calibration and increased accuracy. This telescope also has the capability to see further into the universe, perhaps helping us understand more about the origins and the first formation of galaxies. This telescope was launched into space on 25th December 2021. It is not undergoing calibration and final testing and is soon to show us the marvels of our universe. Here are two images that were taken during testing.

The image on the right was captured by the James Webb Telescope while testing and the one on the right was taken by Spitzer

A comparison image between Hubble and James Webb

With increasing advancements in astronomy and optics, we are sure to receive a visual treat from the James Webb telescope. So, hold on to your hats for more amazing stellar images of our universe.

Glossary

[1] Nebula– A cluster of interstellar clouds comprising cosmic dust, Hydrogen, Helium, and other ionized particles. When these clouds bind together due to the force of gravity, they form stars. (This process occurs over a few million years.

[2] Chromatic aberration– A phenomenon where light rays passing through a lens focus at different points, depending on their wavelength

Delving into Dark Energy and Dark Matter

For the last six decades, scientists at NASA, the Russian Space Agency, and other renowned space research organizations around the world have expanded the knowledge of our universe by a monstrous margin. They have launched a full fleet of telescopes and satellites that have explored various galaxies, planets, and the farthest corners of the universe. As a result, what we considered as fiction 100 years ago is now a reality due to the discovery of new elements and the study of the evolution of the universe from the big bang to the present.

Wilkinson Microwave Anisotropy Probe, the Spacecraft that Gave Our Universe its DOB

The cosmic microwave background is a record of the earliest version of the big bang. The dark ages are where the first stars and galaxies were formed. We must be ever grateful to the Wilkinson microwave anisotropy probe, which made this measurement and gave a coherent picture of the universe we see today. This probe was enabled astronomers and astrophysics to precisely date the age of the universe, which is 13.77 billion years old. Scientists were also able to understand that atoms only made 4.6% of the universe, with the remaining being dark matter and dark energy. The universe consists of regular matter, dark matter, and dark energy. Regular matter constitutes just 5%, consisting of atoms that make up stars, planets, humans, and every other visible object in the universe.

Galaxies, solar systems, and planets are held together by gravity, the universal binder; however, something doesn’t quite add up as galaxies are achieving something that defies gravity. Galaxies are rotating at such speed that the gravity generated by the observable matter doesn’t hold them together as they should have been torn apart long ago causing a cosmic catastrophe. This leads scientists to believe that something that is not observable is in play.

27% of the Universe is Dark Matter

We look up in the universe and see the effects of gravity, how it binds stars, planets, and galaxies together. Now, picture a simulation that lets you re-create the events in the history of the universe. Let’s add up all the comets, black holes, asteroids, stars, and everything we know about to account for the gravity we see. Now add dark matter, the extra gravity, Eureka, the universe becomes what we see. That’s why we know that dark matter is real; we don’t know what it is, but we know that it’s there because we cannot make the universe we see today unless the dark matter is added into the simulation as it perfectly matches with the gravity.

Particle physicists are convinced that there is an exotic particle that doesn’t interact with light, telescopes, or any other equipment but has gravity. These particles are invisible to us but are attracting matter into them and interacting with other elements in a unique and accelerated way. These exotic particles are known as dark matter, which forms the bulk of a galaxy’s mass and the foundation of the universe’s large-scale structure. The nature of dark matter is that it doesn’t emit, absorb, or reflect light, thereby making its presence invisible to the universe. However, its presence is known due to its gravitational pull on the visible matter in space.

Scientists theorize that dark matter could not be matter at all but the gravity from ordinary matter from a nearby other universe or multiverse whose gravitational influence we feel. Mind-blowing, isn’t it? However, there is no hard data of this, but there are theoretical, philosophical reasons to think that a multiverse exists. The first observation of the existence of dark matter was by the Chandra X-ray Telescope in 2007 when it observed the bullet cluster of galaxies.

68% of the Universe is Dark Energy

The Hubble Space Telescope observed very distant supernovae showed scientists that there was a time where the universe was expanding at a much slower rate than today. However, the expanding universe has not been slowing down but has accelerated by a significant margin. No scientist could rationally or theoretically explain this phenomenon, but they knew that something was causing this expansion. Scientists discovered a mysterious pressure in the vacuum of space acting opposite to the force of gravity. This pressure was coined as dark energy, a placeholder term to describe what was observed. No known force could stop or slow down the expansion of the universe.

In fact, in theory, space cannot accommodate or allow this rapid expansion of the universe as it might tear in an unimaginable way. Leading scientists and astrophysics are still baffled at this fact as they cannot explain the nature of dark energy. This energy is needed to measure the geometry of space with the total matter in the universe.

A Breakthrough that Could Re-define Our Understanding of the Universe

The universe is far from being fully understood, and there are numerous theories as to what dark matter and dark energy actually are. Scientists have been racking their brains about what these entities are. In recent times, new methods could detect these energies, thereby leading to a breakthrough in our understanding of the universe. In astrophysics, there is always a capacity to measure something, even if it is unknown to us. For instance, you could measure something falling to the ground by assessing its velocity but not know what the particle is. Likewise, we can measure the sun moving across the sky and build calendars based on that and not know that the Earth revolves around the Sun (This is what our early ancestors did).

Rebecca K Leane is an astroparticle physicist at the SLAC national accelerator laboratory at Stanford University. She believes that Jupiter is an ideal candidate to detect dark matter. It has a large surface area that enables it to capture more incoming particles than any other planet in the solar system.

Exoplanets can also be used to detect dark matter as it does not involve the use of new instruments. When the gravity of exoplanets captures dark matter, it travels to the planetary core to release its energy as heat. The more the dark matter is captured, the more it should heat up the atmosphere. This heat could be captured by NASA’s James Webb Space Telescope, an infrared telescope that is scheduled to launch in November 2021. This telescope is planned to succeed the Hubble and give rise to much larger discoveries that could re-shape the understanding of our universe.

Conclusion

With the launch of the James Webb telescope, scientists could observe various statists of galaxy evolution and compare these observations and analyze theories of the role that dark matter played in that process. In 2025, NASA is planning to launch the Nancy Grace Roman Space telescope designed to unravel the secrets of dark matter and dark energy. It would enable scientists to image exoplanets, explore topics in infrared astrophysics. If this project is successful, it could pave the way to several groundbreaking scientific discoveries that could change the understanding of our existence in the universe!

Galaxies: A Home to The Stars

Did you know that there are more than 200 billion stars in our milky way galaxy? Not just that, it has enough gas to create a few million stars. Every galaxy in our universe is special as it is the home to billions of stars and a few black holes as well. Most galaxies are home to several million earth like planets which are in the habitable zone of their home star. This means that there are over a billion possibilities that we are not the only living beings in the universe.

They come In All Shapes and Sizes

Yes you read it right, all galaxies are not elliptical and boring. They come in varied shapes and sizes. In our observable universe, there are three main types of galaxies which include elliptical, spiral, and irregular. Elliptical galaxies are shaped like a spheroid or an elliptical sphere. On the other hand, spiral galaxies are much spectacular to watch as they appear like a bulged disc with two or more discs which appear like arms. Irregular galaxies have a very haphazard shape and comprise of a lot of star dust and gas.

Our galaxy, the milky way, is a spiral galaxy and we are located at the edge of it. Older stars are clustered at the center of the galaxy and younger ones are spread out. We do not know how many discs our galaxy has because we are inside it and we can’t look at it from a third person view. Neither are we technologically advanced to construct a space probe which can leave our galaxy and take pictures of it.

What’s at Its Center?

The center of our galaxy, the milky way, will appear to remain very bright as there are a cluster of stars present there. According to observations, there is a super massive black hole at the center of our galaxy. This black hole is over four million times the mass of our sun. Scientists theorize that there are super massive black holes at the center of most galaxies. Wheres some speculate that there could be star clusters which are far denser than the ones in nearby irregular galaxies.

How Many Are There In Our Universe?

In the observable universe, there are around 100 billion galaxies. Yes, that is a mammoth number folks. This means that there are several galaxies which are home to harbor life, thereby making it over 1000 billion which are very similar to our earth.

The Milky Way Andromeda Collision

The Andromeda galaxy is a large galaxy which is home to 1 trillion stars, whereas our milky way has only 300 million stars. This is the size difference between these two galaxies.

In about 4 billion years from now, the Andromeda galaxy will collide with our milky way and merge together to form a new galaxy known as Milkdromedia. 3.4 billion years from now, we will be able to view the Andromeda galaxy up close and personal. And trust me, that will be one of the most spectacular sights you could ask for. The collision of these two galaxies will be an absolute spectacle.