Why do astronomers call Uranus and Neptune ice giants?

Uranus and Neptune are called ice giants because they are smaller and compositionally different from Jupiter and Saturn, the gas giants. Jupiter and Saturn are composed of mostly hydrogen and helium, with large mantles of metallic hydrogen (which acts like a metal, due to the pressure and temperature within these planets) and only small cores of rock and ice. This is why they are called gas giants: They are mostly gaseous, with very little rock and ice.

Uranus and Neptune are composed of some hydrogen and helium, but they also contain heavier elements such as oxygen, carbon, nitrogen, and sulfur. Beneath their relatively thin outer shells of hydrogen and helium, these planets’ mantles are largely made of compressed, slushy water and ammonia. The ice giants’ rocky, icy cores are also proportionally larger than the amount of gas they contain, unlike the gas giants. This is why Uranus and Neptune are called ice giants.

The “ice giant” terminology took hold in the 1990s when researchers realized Uranus and Neptune were compositionally different from Jupiter and Saturn. Classifying them differently better reflects the variations in the formation of the outer planets, giving astronomers a clearer picture of how our solar system and others formed.

Credit : Astronomy.com 

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Which moon of Neptune revolves in the opposite direction of its other moons?

Triton is the largest of Neptune's 13 moons. It is unusual because it is the only large moon in our solar system that orbits in the opposite direction of its planet's rotation?a retrograde orbit.

Scientists think Triton is a Kuiper Belt Object captured by Neptune's gravity millions of years ago. It shares many similarities with Pluto, the best known world of the Kuiper Belt.

Like our own moon, Triton is locked in synchronous rotation with Neptune?one side faces the planet at all times. But because of its unusual orbital inclination both polar regions take turns facing the Sun.

Triton has a diameter of 1,680 miles (2,700 kilometers). Spacecraft images show the moon has a sparsely cratered surface with smooth volcanic plains, mounds and round pits formed by icy lava flows. Triton consists of a crust of frozen nitrogen over an icy mantle believed to cover a core of rock and metal. Triton has a density about twice that of water. This is a higher density than that measured for almost any other satellite of an outer planet. Europa and Io have higher densities. This implies that Triton contains more rock in its interior than the icy satellites of Saturn and Uranus.

Triton's thin atmosphere is composed mainly of nitrogen with small amounts of methane. This atmosphere most likely originates from Triton's volcanic activity, which is driven by seasonal heating by the Sun. Triton, Io and Venus are the only bodies in the solar system besides Earth that are known to be volcanically active at the present time.

Triton is one of the coolest objects in our solar system. It is so cold that most of Triton's nitrogen is condensed as frost, giving its surface an icy sheen that reflects 70 percent of the sunlight that hits it.

NASA's Voyager 2?the only spacecraft to fly past Neptune and Triton?found surface temperatures of -391degrees Fahrenheit (-235 degrees Celsius). During its 1989 flyby, Voyager 2 also found Triton has active geysers, making it one of the few geologically active moons in our solar system.

Credit : NASA Science 

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Does Neptune have rings?

Neptune has five rings: Galle, Le Verrier, Lassell, Arago, and Adams. Its rings were named after the astronomers who made an important discovery regarding the planet. The rings are composed of at least 20% dust with some of the rings containing as much as 70% dust; the rest of the material comprising the rings is small rocks. The planet’s rings are difficult to see because they are dark and vary in density and size.  Astronomers think Neptune’s rings are young compared to the age of the planet, and that they were probably formed when one of Neptune’s moons was destroyed.

The Galle ring was named after Johann Gottfried Galle, the first person to see the planet using a telescope. It is the nearest of Neptune’s rings at 41,000–43,000 km.  The La Verrier ring was named after the man who predicted Neptune’s position. Very narrow, this ring is only about 113 kilometers wide. The Lassell ring is the widest of Neptune’s rings. Named after William Lassell, it lies between 53,200 kilometers and 57,200 kilometers from Neptune, making it 4,000 kilometers wide.  The Arago ring is 57,200 kilometers from the planet and less than 100 kilometers wide.

The outer ring, Adams, was named after John Couch Adams who is credited with the co-discovery of Neptune. Although the ring is narrow at only 35 kilometers wide, it is the most famous of the five due to its arcs. Adams’ arcs are areas where the material of the rings is grouped together in a clump. Although the Adams ring has five arcs, the three most famous ones are Liberty, Equality, and Fraternity. The arcs are the brightest parts of the rings and the first to be discovered. Scientists are unable to explain the existence of these arcs because according to the laws of motion they should distribute the material uniformly throughout the rings.

The rings of Neptune are very dark, and probably made of organic compounds that have been baked in the radiation of space. This is similar to the rings of Uranus, but very different to the icy rings around Saturn. They seem to contain a large quantity of micrometer-sized dust, similar in size to the particles in the rings of Jupiter.

Credit : Universe Today 

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Which is the smallest of the giant planets?

Neptune is the fourth largest planet in terms of diameter, making it the smallest in physical size of the gas giants. The average distance from the center of the planet to its surface is 15,299 miles (24,622 kilometers). But like most spinning bodies, Neptune's rotation causes it to bulge slightly around the equator. The resulting shape is known as an oblate spheroid. The radius at the poles is 15,125 miles (24,341 km), slightly smaller than the equatorial radius of 15,388 miles (24,764 km). The average diameter across the planet is 30,598 miles (49,244 km), almost four times the diameter of Earth.

Although Neptune comes in fourth in terms of diameter, it ranks third in terms of mass, ahead of Uranus. The gas giant weighs in at 1.02 x 1026 kilograms, or 102 trillion trillion kilograms. It is more than seventeen times as massive as Earth.

The rock, ices, and gas that make up the icy giant fill a volume of 15 trillion cubic miles (62 trillion cubic kilometers), almost 58 times the volume of Earth.

The density of Neptune is 1.638 grams per cubic centimeter. The low density indicates that, like Uranus, its atmosphere is made up of more ices than Saturn and Jupiter, causing scientists to call it an "icy giant". The distance to Neptune from the sun keep the planet's temperature low through the year, although some astronomers suspect the planet originally formed closer to the star.

Despite hosting a significantly lower mass, Neptune's surface gravity is second only to Jupiter.

Credit : Space.com

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Whose work provided the first evidence for the existence of dark matter?

Dark matter is a mysterious substance thought to compose perhaps about 27% of the makeup of the universe. What is it? It’s a bit easier to say what it isn’t.

It isn’t ordinary atoms, the building blocks of our own bodies and all we see around us. Atoms make up only somewhere around 5% of the universe, according to a cosmological model called the Lambda Cold Dark Matter Model (aka the Lambda-CDM model, or sometimes just the Standard Model).

Dark matter isn’t the same thing as dark energy. Dark energy makes up some 68% of the universe, according to the Standard Model.

Dark matter is invisible; it doesn’t emit, reflect or absorb light or any type of electromagnetic radiation such as X-rays or radio waves. Thus, instruments can’t detect dark matter directly, as all of our observations of the universe, besides detecting gravitational waves, involve capturing electromagnetic radiation in our telescopes.

Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities. They should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure. Imagine it as only the label on the LP, causing the galaxy to have a consistent rotation speed from center to edge.

Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas met much resistance from the astronomical community, but her confirmed observations now create pivotal proof of the existence of dark matter. In honor of this crucial and historic piece of detective work toward establishing the existence of dark matter, the revolutionary Large Synoptic Survey Telescope recently received the name Vera C. Rubin Observatory.

Credit : Earth Sky 

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What is a galactic year?

Our Sun orbits the Supermassive black hole that is at the centre of our galaxy, the Milky Way galaxy at a distance of about 27,000 Light Years. You'll probably be surprised to hear that the Canis Major dwarf galaxy is nearer to us than the galactic centre.

Stars in an Elliptical Galaxy such as the Milky Way orbit the centre and the Milky Way is no different. The time it takes for the Sun to complete a full orbit of the Supermasssive is known as the Galactic Year. There might be an Universe Year but we'll never know probably.

The time it takes to complete a full orbit of the galaxy is about 225 - 250 million Earth years. 250 Million Years ago was the Triassic Period when the first dinosaurs were walking the Earth. If we turned the time back one Galactic Year, Earth would be much different, no Internet, no Mobiles, not even humans could be found orbiting the Earth.

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Is the sun the only star in the Milky Way?

The Milky Way is the galaxy in which Earth resides. Part of it is visible on a clear night (from sufficiently dark locations) as a thick opaque band of stars and dust stretching across the sky. We can see thousands of these stars with the naked eye, and many more with a telescope. But how many stars are in the Milky Way?

"It's a surprisingly difficult question to answer," said David Kornreich, an assistant professor at Ithaca College in New York. "You can't just sit around and count stars, generally, in a galaxy." 

Even in the Andromeda galaxy — which is bright, large and at 2.3 million light-years away relatively close to Earth  — we can distinguish only the largest and brightest stars. A sun-size star would be too difficult for us to see. 

So is there any way to figure out how many stars are in the Milky Way for sure? 

According to Jos de Bruijne, a scientist at the European Space Agency (ESA) who works on the galaxy-mapping Gaia mission, the current estimate is between 100 to 400 billion stars. Getting to a definitive number, de Bruijne told Space.com, will be difficult. 

The Gaia mission, in orbit since 2013, has managed to map positions of 1.7 billion stars in the sun's neigborhood up to the distance of 326 light-years. While astronomers could extrapolate those numbers to model the entire galaxy, even Gaia struggles to see some of the faintest and smallest stars and its results are therefore not perfectly accurate.

"The fundamental problem is to measure the luminosity [distribution] for very faint red dwarfs and then extrapolate to the brown-dwarf limit," de Bruijne told Space.com.

Red dwarfs are the most common stars in the universe and also the longest-lived ones. However, because of their low luminosity they are sometimes hard to spot. Brown dwarfs are even dimmer. These are basically failed stars that didn't manage to accumulate enough material to kick-start nuclear fusion in their core. They are therefore something between a star and a planet and therefore even more difficult to spot than faint red dwarfs, especially at long distances.

"A second complication for the entire story are double stars, the frequency of which is still not perfectly characterised," de Bruijne added. 

De Bruijne expects that by the end of Gaia's mission in 2025, scientists will have a somewhat better idea about the number of stars in our galaxy but "significant uncertainties will likely remain". 

Credit : Space.com

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Is the Milky Way constantly moving?

The planets in our solar system orbit around the sun. One orbit of the Earth takes one year. Meanwhile, our entire solar system – our sun with its family of planets, moon, asteroid and comets – orbits the center of the Milky Way galaxy. Our sun and solar system move at about about 500,000 miles an hour (800,000 km/hr) in this huge orbit. So in 90 seconds, for example, we all move some 12,500 miles (20,000 km) in orbit around the galaxy’s center.

Our Milky Way galaxy is a big place. Even at this blazing speed, it takes the sun approximately 225-250 million years to complete one journey around the galaxy’s center.

What about the Milky Way galaxy? Yes, the whole galaxy could be said to rotate, but like our sun, the galaxy is spinning at different rates as you move outward from its center. At our sun’s distance from the center of the Milky Way, it’s rotating once about every 225-250 million years – defined by the length of time the sun takes to orbit the center of the galaxy.

The planets in our solar system orbit (revolve) around the sun, and the sun orbits (revolves) around the center of the Milky Way galaxy. We take about 225-250 million years to revolve once around the galaxy’s center. This length of time is called a cosmic year.

Credit : Earth Sky 

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What is a career as a data scientist?

Netflix uses viewership data to give better movie recommendations. Facebook uses past interactions to send more targeted ads to users. Google Maps estimates your ETA (Estimated Time of Arrival) based on huge amounts of data accumulated from other people using the app on the same route.

These are all examples of data science being put to use to gain a deeper level of understanding. In this way, data scientists are like detectives, finding patterns out of data to help businesses make smarter decisions.

What's this career about?

Data scientists are the game changers for any organization. They simplify big data through coding and algorithms and turn it into a problem-solving solution for the business.

A data scientist's work typically involves making sense of messy, unstructured data, collected from sources such as smart devices, surveys, social media feeds and emails.

Their work includes framing relevant questions which need to be answered, and collecting huge amounts of data available on the internet. The importance of gathering and collecting data is crucial as it enables organisations to determine and thus influence trends in a particular industry.

Then, using modelling, statistics and analytics programmes, data scientists organize the data into a predictive model and analyse the data. Based on their analysis, changes to existing systems and strategies are recommended.

Often, these scientists are required to present the analysed results, trends, opportunities and even weaknesses in an understandable manner across various teams. So, it is highly important for them to be effective communicators, leaders and team members as well as high-level analytical thinkers.

Sometimes, they need to write new algorithms to solve issues if nothing existing works. This also means that data scientists have to build data science tools if need be.

They work cross functionally with other teams throughout their organization, such as marketing, customer success, and operations.

With data playing an increasingly important part in the economy, data scientists are needed in every industry you can think of. From healthcare to sports, finance, and e-commerce (not to mention the traditional sciences), the applications are almost limitless. For keen lifelong learners, this makes data science a cornucopia of opportunities to practise and grow.

How do I get there?

You'll need at least a degree in Mathematics, Statistics, Economics, Engineering or Computer Science to work as La data scientist. Along with a degree, you are supposed to know programming languages such as R, Python, SQL, Cor Java and have strong database design and coding skills. Then you can go for a postgraduate course in business analytics, big data or data science. During this course, you'll study subjects like machine learning, data analytics, statistics, data modelling, business analysis, data visualisation, cloud computing, database systems, internet technologies and algorithms.

What key skills do I need?

  • Excellent analytical and problem-solving skills
  • Good communication and presentation skills in order to explain your work to people who don't understand the mechanics behind data analysis.
  • Effective listening skills in order to understand the requirements of the business.
  • Drive and the resilience to try new ideas if the first one doesn't work. You'll be expected to work with minimal supervision, so it's important that you're able to motivate yourself.
  • Planning, time management and organisational skills.
  • The ability to deliver under pressure and to tight deadlines.
  • Great attention to detail.
  • Team-working skills and a collaborative approach to sharing ideas and finding solutions.


  • Indian Statistical Institute (ISI), Kolkata offers courses in statistics.
  • IIT Kanpur, Mumbai, Bangalore, Kolkata, Kharagpur, offer B.S. in Mathematics and Scientific Computing.
  • IIT Roorkee offers a postgraduate certificate programme in Data Science & Machine Learning.
  • Indian School of Business (ISB), Hyderabad; S.P. Jain School of Global Management, Mumbai; Great Lakes Institute of Management, Chennai offer courses in Business Analytics.
  • Indian Institute of Science Education and Research, Pune and various other locations offer BS-MS programmes.

Pay package

Data scientists usually start with Rs. 6-8 lakhs per annum. Their salary can increase steadily over the first 5-10 years if they keep sharpening their skills. Thus it is always better to keep gaining knowledge in advanced programming, data modelling, machine learning and more. Most of the related jobs are in Bengaluru, followed by Gurgaon, Pune, Mumbai and Hyderabad.

Employment profile

Data is everywhere, hence data science has emerged as an attractive career option. Demand for skilled data scientists is massive as organizations are focusing more and more on using the insights from this data to evaluate progress, build solutions and make decisions.

The main career opportunities available are in data science, data analytics, big data engineers, big data managers and data architects. Sectors like information technology, telecom, manufacturing, finance and i insurance are dependent on data science to make smarter decisions that are based on the data that indicate consumer preferences and help market it to the right group of people. Small start-ups are generating a massive amount of data every day, thus resulting in increased hiring.

Credit :  Dr. Vibha Gupta (The Teenager Today)

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I have a very weak memory

I am a 17-year-old boy studying in Std XI. My problem is that I have a very weak memory. When the teacher gives a lecture in class, I think I can remember everything, but after a few days I forget. I want to come up in life but it will not be possible with this kind of a memory. Sometimes I think of discontinuing my studies. What should I do to improve my memory and get good marks?

You sound discouraged that you cannot remember everything from your teacher's lecture. But you know what? Thinking that you can remember - but then forgetting - is normal!

Do look up The Forgetting Curve on the Internet and you will realise that the biggest drop in remembering happens soon after learning. Not only this, but memory also becomes weaker with time, so even if you revise, you will remember only some of it after a week. Our nervous system works on the principle 'Use it or lose it'. Hence, revise at regular intervals.

For good memory, you need to: 1) Take an interest in the topic it is the key to remembering; 2) Make meaning: connect the topic to something you know. E.g. Look for ways that you can use it in real life. 3) Organize your information - chunk or group the information into topics and sub-topics so that you remember one group together; also, transfer information from text form to diagrams, mind maps, concept maps, tables, etc.. 4) Make it fun - if you associate something funny with certain topics, you won't forget them. Fun is also about connecting it to something you enjoy, e.g., a sport, or movies, etc. And fun is also about playing while you learn. 5) Solve practice papers - lots of them.

Finally, if you would like to, you can get the following books: Learning How to Learn by Barbara Oakley & Terence Sejnowski and Mindshift: Break Through Obstacles to Learning and Discover Your Hidden Potential by Barbara Oakley; Improve your Memory, Study and Reading Skills Creatively by V. Tucker (Better Yourself Books, Mumbai).

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We stopped talking to each other

I am a girl of 16, studying in Std XI. I made one of my classmates my brother, and shared everything with him. But our classmates started teasing both of us as they didn't know that we shared a brother-sister relationship. Because of this, we stopped talking to each other and, for the last one and a half years we have not even seen each other. I would like to talk to him and I feel that he too wants to talk to me. What should we do?

You are missing your friend and 'brother' a lot and want to talk to him. Unfortunately, the fact that you both stopped talking to each other makes you both look guilty even if you are not.

People talk if they sense something in the air. Perhaps the closeness shown by both of you made them think you both were a romantic pair? Reflect and you will get the answer. If people did talk but you felt sure that he was your brother and nothing else, then there was no need to listen to them even if they teased you. In India, we have so many ways to show a brother-sister relationship - tying a rakhi to him can show that you have adopted him as your brother, and he has adopted you as a sister even if you are not related by blood. Addressing him with a word meaning brother in one of our many languages - in front of others will make things clear to all.

But first, you both need to be sure that the relationship is still that of a brother-sister, or just friends, or more. And the only way to find out is to meet and take it from there.

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I don't want to study there anymore

I am studying in an ICSE school. I feel that the school is not providing me with what I want the best study material, among other things. Instead, the teachers are very corrupt and demotivating. I don't want to study there anymore. How can I convince my parents about this?

Looks like you feel unhappy in your current school with 'corrupt' and 'demotivating' teachers and lack of the best study material.

Start by helping yourself while you are still in this school since you can change only in the next academic year. See it as a challenge you need to deal with on your way to life success. Learn the art of both taking and making notes. Learn the art of research: there are also so many ICSE study guides and videos available for reference. Collaborate: Work with your classmates to resolve difficulties or study together as study buddies. These skills will prove helpful in higher education, too.

If there are other students facing the same issues, perhaps your parents can approach the Parent-Teacher Association who can take it up with the school authorities in the right manner.

Simultaneously, list what you want from a school - you have already mentioned 'best study material'. Then find out which schools that offer the things you want and within the fee budget of your parents. Create a chart/Excel sheet and share it with your parents with reasons and examples of why it would be better to go to one of these schools. Ask them for their views too.

If you and your parents agree, great. If not, you will already have learned a few tools on how to be successful despite adversity!

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His memory still haunts me

A year and a half ago, I met a boy with whom I fell deeply in love. We loved each other and that was it; neither I nor he made any commitment towards our relationship. We never had a date or anything. Every evening, I used to go to the beach to view the sunset and would always find him sitting there, perhaps waiting for me. Today, it has been three months since his death. Although I do not feel any emotion, I can still feel his presence. I am unable to move on as his memory still haunts me. Please help me.

The tragic death of this boy whom you loved has shocked you. Looks like you feel numb inside and are unable to feel your grief. Please know that it is okay to give yourself some time to come to terms with his going.

While he may not be present in physical form, you do feel his presence. Perhaps this is his message to you: That there is no need for you to 'move on' but there is a need to acknowledge that he has gone and he will remain with you in your memory.

It is important to honour this connection that you feel and express it. Perhaps you can create a small space at home for a short period of time to honour his memory. You could draw something that reminds you of him or keep a picture or object that you connect with him maybe a picture of the sunset? Then light a diya or a candle in memory of him every day for some time. Keep some flowers. If you prefer to express yourself in writing, you can keep a journal of your feelings. At the same time, if you feel you need more help, it would be good if you can meet a counsellor in person.

Remember that while you grieve for him right now, he would certainly want you to live your life and blossom over the years. Perhaps he wanted you to find your inner strength and has become your invisible guide.

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I can't stop thinking about her and our future

I am in love with a girl. I told her that I had feelings of love for her and she told me that she had the same feelings for me. She also said to me that we can handle these things later after we settle in our lives. I agreed with her. But I can't stop thinking about her and our future and whether we have a good destiny in store for us.

Looks like you are so caught up in the unknown future that you are worried and anxious today.

If you notice, we always say the words 'to fulfil one's destiny'. It means that 'good destiny' is not 'in store' for us, but we create it by working to achieve our potential and successfully handling all problems that come our way.

Famous author Deepak Chopra says, "Our future is created from choices we make every minute." Fulfilling your destiny depends on what you choose to do today. If you choose to worry about your future, then the outcome will be less than happy. Your attention will deviate from all that can help you live a good life. For example, focusing on studies will lead to a good qualification, which leads to a satisfying job/career, which provides income, which helps you settle well in life. Similarly, focusing on building a friendship with this girl today instead of overthinking about what might happen tomorrow helps build a sound relationship that can withstand any storms in life.

So, roll up your sleeves, and discover the joys of today, while preparing for tomorrow.

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Am I being very possessive?

I am in Class 11 and I have a girlfriend. She likes to hang out with boys all the time except with me, i.e., she talks to other boys a lot. But I know that she is serious about me. I don't want her to go around with or talk with other boys... is this correct or am I being very possessive?

You feel insecure when your girlfriend talks more to other boys. You would like her to stop doing this, however, you are worried that you are being very possessive'. Perhaps you fear that she may leave you? Or that you're not good enough? If unresolved, this can lead to suspicion and trust issues between the two of you.

You say that your girlfriend likes to hang out with boys all the time except with you and yet you say that you know that she is 'serious about you. If she spends more time with other boys at present than with you and you are aiming for a long-term relationship, both need to be okay with it, or you both need to evaluate where your relationship is going.

Reflect on what are your fears and be clear on what will make you feel secure. Also reflect on what you want your relationship to be like; how much time you'd like together, what is okay and what is not okay. Then ask for time and share your feelings with her, discuss and come to a mutual agreement about how what will work best for you both and what you both will do to enhance your relationship. Also take steps to enhance your own self esteem.

If insecurity has been plaguing you for some time and it persists, do connect face-to-face with a counsellor who will help you to process your feelings so that you enjoy happier relationships.

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