planets – 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

Why A Ring Around Saturn?

Why a ring around Saturn? Because she’s engaged! As the second-largest planet in the solar system, Saturn is a gas giant adorned with a gorgeous icy ring that adds flair to its personality. It is made up of Hydrogen and Helium gases making up a huge ball that is home to one of the most breath-taking landscapes in our solar system. Saturn is named after the Roman god of agriculture and wealth, also the father of Jupiter.

What is Saturn Made up of?

Before we understand why Saturn has a ring around it, we need to know the history of how the planet was formed. 4.5 billion years ago, Saturn was formed when other planets in the solar system took shape. Gravity pulled swirling dust and gas in to become this enormous second-largest gas giant in the solar system. At its core, there are dense metals like iron and nickel that are surrounded by rocky material and other compounds solidified by intense pressure and heat. Its core is very stable and integral as it is enveloped by a layer of liquid hydrogen similar to Jupiter’s core but considerably smaller.

Did you know that Saturn can float on water if dropped in a planet-sized tub? Yes, that’s right, the planet’s average density is less than water due to its gas composition. Saturn does not have a true surface as it comprises swirling gas and liquids deep down. Let us take a journey into Saturn by flying a space drone into the planet’s atmosphere. As the drone flies into Saturn, it would melt and vaporize well before it hits the planet’s surface. This is due to the extreme pressure and temperature of the planet that could crush, melt, and reduce the spacecraft into smithereens. Also, the planet lacks a crust or surface as it is only a ball of swirling gases.

The Atmospheric Composition

Let us hypothetically design a specific suit that can withstand the hostile conditions on Saturn. As you are dropped into Saturn, you will be able to observe faint stripes, get streams and storms. They will be of different shades of yellow, brown, and grey. You will be swept away by winds in the upper atmosphere that reach a speed of 1,600 feet per second. The pressure will be so immense that it would squeeze gas into a liquid form. But you will not be affected by this as the hypothetically created suit would be able to withstand this pressure.

As you make your way to the planet’s North pole, you will be mesmerized by a six-sided jet stream. This stream that resembles a hexagon was first observed by the Voyager 1 spacecraft in 1980. This hexagon spans at 20,000 miles across, with a wavy jet stream of wind hitting you at 322 km/hr with a massive rotating storm at the center. Saturn’s smaller magnetic field is smaller than Jupiter’s but 578 times more powerful than Earth’s. It has an enormous magnetosphere that covers the rings and many of the satellites. The magnetosphere behaves like electrically charged particles and is influenced by Saturn’s magnetic field than the solar wind.

How Did the Ring Form?

When Saturn was formed, it is believed that pieces of asteroids and comets of shattered moons broke up before they reached the planet, thanks to its strong gravity. Since these asteroids were very far away from the Sun, they were coated with ice due to the extreme cold. The planet’s ring comprises dust-sized icy grains to large chunks as big as a house or even a mountain. These rings would look white from the surface, with each ring orbiting around the planet at a different speed.

Saturn’s ring extends up to 175,000 miles from the planet, but the vertical height is 30 feet in main rings. The ring was named in the order they were discovered alphabetically, with the main ones being A, B, and C. Fainter and more recently discovered rings were D, E, F, and G. The rings D, C, and B are close to the inner atmosphere of the planet and rings A, F, G, and E were farther out. Also, there is a faint ring in the orbit of Saturn’s moon Pheobe.

Saturn’s rings are truly an amazing sight to behold. You can visit a nearby observatory to check out that marvelous sight on the right day. Just make sure to search on the internet and find the day when Saturn will be visible in the right sky and drive to the observatory.

Why Are Planets Round?

Have you ever wondered why planets are shaped round? Why aren’t they shaped like pyramids, cubes, or discs? Well, if they were shaped like discs, it would surely be a paradise for flat earthers. 🤣😂 Jokes apart, let’s understand the reason why planets are spherical or oblate spheroid in shape.

When the solar system was formed, planets formed from the remnants of the protoplanetary disc that comprised of asteroids. These asteroids are large space rocks that bonded together to form the planets we see today. However, you may wonder, although each planet does not constitute just rocks but also gases, why do all elements bind together in the form of a sphere?

Why a Sphere?

Well, the simple answer is gravity. Around 4.5 to 5 billion years ago, space rocks from the protoplanetary disc that orbited around the Sun were the building blocks for planets. This protoplanetary disc was formed due to the aftermath of the birth of our star, the Sun. When large space rocks or space debris and gases bump on each other, they bind together to form large planet-size objects. Over a period of time, these large rocks gather enough mass to have gravity, the key force that holds elements together in space. Once the planet is big enough, it automatically begins to clear a path around the star it orbits.

Gravity works in one way; it pulls equally from all sides, specifically from the centre to the edges. When materials of large mass bind together, gravity starts acting on them in this manner, and they clump together to form a sphere. Whether it is just space rock or high-density gas and space debris, gravity acts in the same manner and pulls materials inward, giving them a spherical shape. Gravity holds planets together, it’s the universal glue.

Are all Planets a Perfect Sphere?

Not really; most planets are slightly bulged in the middle, similar to a basketball. For instance, our Earth is slightly flat at the poles but bulged along the equator, giving it the shape of an oblate spheroid. Some planets in our solar system, like Mercury and Venus, are the roundest among all, whereas others are thicker in the middle. For instance, Saturn and Jupiter are thicker in the middle.

Try this, soak a tennis ball in water and throw it in the air by giving it a little spin. What do you observe? The water on the ball would dissipate along the outer edges in a sprinkling manner. This is the same in the case of planets too, when large planets spin, materials on the outer edge move faster than the ones on the inside to keep up. This is because things along the edge have to travel the farthest and the fastest.

Saturn and Jupiter are large planets with a fast spin; this results in a large bulge along the middle like an extra width. This width is known as the equatorial bulge. Saturn is the planet that is thickest around the middle with a 10.7% bulge and Jupiter with a 6.9% bulge in our solar system.

Gravity, the binding force in the universe, always acts inward; that’s why all materials accumulate and bind together form as a sphere and not as a pyramid, cube, or disc. This law applies to not just the planets in our solar system but to all planets in the universe.