Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky

A cloud of collapsing gas created our Sun, the first thing to form in our solar system. This happened about 4½ billion years ago.

Then the planets began to emerge, as the billions of particles of gas and dust left over from the Sun’s formation became a flattened disk.

Known as a protoplanetary disk, it was enormous and surrounded the Sun for billions of miles. Within the disk, the gas and dust particles started to collide, solidify and stick together, like snowflakes clumping together to form snowballs.

As the particles clung together, the microscopic grains became pebble-size objects and then grew and grew. Some became rocks the size of baseballs, others the size of a house, and a few as big as a planet.

This process, called accretion, is how everything in the solar system – planets, moons, comets and asteroids – came into being.

The ice line

By studying computer models and observing the creation of other star systems, astronomers like us have learned a lot about the early days of our solar system.

When the Sun was still forming and the protoplanetary disk was making planets, there was a distance from the Sun where it was cold enough for ice to gather. That place, the ice line – sometimes called the snow line – was in what’s now the asteroid belt, which is between Mars and Jupiter.

Today, of course, ice is found on almost every planet, even on Mercury. But back then, only the young protoplanets beyond the ice line were cold enough to have it. The ice, gas and dust, slamming into each other for millions of years, accumulated into enormous bodies that ultimately became giant planets – Jupiter, Saturn, Uranus and Neptune.

While all this was happening, the smaller planets inside the ice line were forming too. But with less raw material to work with, Mercury, Venus, Earth and Mars took much longer.

Today, it’s believed that Jupiter and Saturn, the largest planets, were the first to fully form, both within a few million years. Uranus and Neptune were next, within 10 million years. The inner planets, including Earth, took at least 100 million years, maybe more.

To put it another way, the four planets closest to the Sun are the youngest; the two planets farthest out, the next youngest; and the two in between, the oldest. The difference in age between the youngest and oldest planets is perhaps 90 million years.

That sounds like an enormous age difference, but in space, 90 million years isn’t really that long – less than 1% of the total time the universe has been around. One way to consider it: Think of Earth as a little sister with a big brother, Jupiter, who’s 2 or 3 years older.

Location, location, location

Soon after formation the giant worlds began to migrate, moving inward toward the Sun or outward away from the Sun, before finally settling into their final orbits.

For instance, Neptune migrated outward, switching places with Uranus, and pushed a lot of the small, icy bodies into the Kuiper Belt, a place in the outer solar system that’s home to dwarf planets Pluto, Eris and Makemake and millions of comets.

Meanwhile, Jupiter moved inward, and its massive gravity forced some forming planets into the Sun, where they disintegrated. Along the way, Jupiter flung some smaller rocks out of the solar system altogether; the rest went to the asteroid belt.

But most critically, as Jupiter settled into its own orbit, it moved all of the forming objects and likely finalized the location of the remaining inner planets, including Earth.

All of Jupiter’s tugging helped put our planet in the so-called “Goldilocks zone,” a place just the right distance from the Sun, where Earth could have liquid water on its surface and the right temperature for life to evolve. If Jupiter hadn’t formed the way it did, it’s entirely possible life would not have ignited on Earth – and we would not be here today.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Christopher Palma, Teaching Professor of Astronomy & Astrophysics, Penn State and Lucas Brefka, Ph.D. Student in Astronomy & Astrophysics, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why do dolphins jump out of the water?

Charlize, age 8, Melbourne

Have you ever seen images of dolphins jumping out of the waves and performing impressive acrobatics in the air? Or maybe you’ve seen it in real life?

When a dolphin jumps, it can launch its whole body out of the water. While it looks like fun, it must also be hard work!

So, why do dolphins jump out of the water? There are several possible reasons. Let’s jump in and explore them.

To stay in touch

Dolphins are social animals and live in groups. But it’s hard to see long distances underwater. So, they use the power of sound to stay in contact with each other.

Sound travels much farther underwater than through the air. When dolphins jump, the slap of the landing makes a loud noise, and would be heard some distance away.

Some species, such as spinner dolphins, use jumping to communicate their location to other group members, especially at night. This helps them keep track of each other.

As an aside, spinner dolphins are very skilled jumpers. As the name suggests, they spin up to seven times in the air before landing back in the water!

The need for speed

Have you ever tried to walk underwater? You will have felt how hard it is. That’s because water is more dense than air, which creates a “drag”, or resistance.

Dolphins have streamlined bodies to reduce drag, but they still feel it. So, if they want to travel quickly – for example, if they are trying to escape a predator or hunt fish – they sometimes jump.

While in the air, they travel faster than they would through water, and also save energy.

To gather food

Some dolphins weigh less than 50 kilograms, such as the Hector’s dolphin. Others weigh several tonnes, such as an orca.

Either way, when a dolphin crashes back into the water, you can be sure it makes quite a noisy splash.

Some dolphin species, such as dusky dolphins, use this noise to herd fish at the surface to make them easier to capture.

Shaking off hitchhikers

Fish called remoras can attach themselves to dolphins using a sucker on their head. This is good for the fish, because it can keep them safe and they have plenty to eat, such as small parasites and old bits of dolphin skin.

While the remoras don’t hurt the dolphin, they probably slow it down. So dolphins may try to get rid of the little hitchhikers by jumping to dislodge them.

Fighting and frolicking

Dolphins are highly intelligent animals. They have big brains and can learn tricks and solve puzzles. With intelligence also come other traits: playfulness and social behaviour.

Sometimes, that social behaviour can end in a “fight”. Dolphin experts say two dolphins jumping around together might be actually trying to hit each other!

Dolphins also love to frolic – not just with each other but with other marine mammals such as whales and sea lions, with turtles – or even just a piece of seaweed! So they might jump as some sort of “game”.

As you can see, dolphins may jump for a range of reasons – sometimes just because it’s really fun!

Dr Katharina J. Peters, Lecturer in Biological Sciences, University of Wollongong

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

How does the camera on the James Webb Space Telescope work and see so far out? – Kieran G., age 12, Minnesota

Imagine a camera so powerful it can see light from galaxies that formed more than 13 billion years ago. That’s exactly what NASA’s James Webb Space Telescope is built to do.

Since it launched in December 2021, Webb has been orbiting more than a million miles from Earth, capturing breathtaking images of deep space. But how does it actually work? And how can it see so far? The secret lies in its powerful cameras – especially ones that don’t see light the way our eyes do.

I’m an astrophysicist who studies galaxies and supermassive black holes, and the Webb telescope is an incredible tool for observing some of the earliest galaxies and black holes in the universe.

When Webb takes a picture of a distant galaxy, astronomers like me are actually seeing what that galaxy looked like billions of years ago. The light from that galaxy has been traveling across space for the billions of years it takes to reach the telescope’s mirror. It’s like having a time machine that takes snapshots of the early universe.

By using a giant mirror to collect ancient light, Webb has been discovering new secrets about the universe.

A telescope that sees heat

Unlike regular cameras or even the Hubble Space Telescope, which take images of visible light, Webb is designed to see a kind of light that’s invisible to your eyes: infrared light. Infrared light has longer wavelengths than visible light, which is why our eyes can’t detect it. But with the right instruments, Webb can capture infrared light to study some of the earliest and most distant objects in the universe.

Although the human eye cannot see it, people can detect infrared light as a form of heat using specialized technology, such as infrared cameras or thermal sensors. For example, night-vision goggles use infrared light to detect warm objects in the dark. Webb uses the same idea to study stars, galaxies and planets.

Why infrared? When visible light from faraway galaxies travels across the universe, it stretches out. This is because the universe is expanding. That stretching turns visible light into infrared light. So, the most distant galaxies in space don’t shine in visible light anymore – they glow in faint infrared. That’s the light Webb is built to detect.

A golden mirror to gather the faintest glow

Before the light reaches the cameras, it first has to be collected by the Webb telescope’s enormous golden mirror. This mirror is over 21 feet (6.5 meters) wide and made of 18 smaller mirror pieces that fit together like a honeycomb. It’s coated in a thin layer of real gold – not just to look fancy, but because gold reflects infrared light extremely well.

The mirror gathers light from deep space and reflects it into the telescope’s instruments. The bigger the mirror, the more light it can collect – and the farther it can see. Webb’s mirror is the largest ever launched into space.

Inside the cameras: NIRCam and MIRI

The most important “eyes” of the telescope are two science instruments that act like cameras: NIRCam and MIRI.

NIRCam stands for near-infrared camera. It’s the primary camera on Webb and takes stunning images of galaxies and stars. It also has a coronagraph – a device that blocks out starlight so it can photograph very faint objects near bright sources, such as planets orbiting bright stars.

NIRCam works by imaging near-infrared light, the type closest to what human eyes can almost see, and splitting it into different wavelengths. This helps scientists learn not just what something looks like but what it’s made of. Different materials in space absorb and emit infrared light at specific wavelengths, creating a kind of unique chemical fingerprint. By studying these fingerprints, scientists can uncover the properties of distant stars and galaxies.

MIRI, or the mid-infrared instrument, detects longer infrared wavelengths, which are especially useful for spotting cooler and dustier objects, such as stars that are still forming inside clouds of gas. MIRI can even help find clues about the types of molecules in the atmospheres of planets that might support life.

Both cameras are far more sensitive than the standard cameras used on Earth. NIRCam and MIRI can detect the tiniest amounts of heat from billions of light-years away. If you had Webb’s NIRCam as your eyes, you could see the heat from a bumblebee on the Moon. That’s how sensitive it is.

Because Webb is trying to detect faint heat from faraway objects, it needs to keep itself as cold as possible. That’s why it carries a giant sun shield about the size of a tennis court. This five-layer sun shield blocks heat from the Sun, Earth and even the Moon, helping Webb stay incredibly cold: around -370 degrees F (-223 degrees C).

MIRI needs to be even colder. It has its own special refrigerator, called a cryocooler, to keep it chilled to nearly -447 degrees F (-266 degrees C). If Webb were even a little warm, its own heat would drown out the distant signals it’s trying to detect.

Turning space light into pictures

Once light reaches the Webb telescope’s cameras, it hits sensors called detectors. These detectors don’t capture regular photos like a phone camera. Instead, they convert the incoming infrared light into digital data. That data is then sent back to Earth, where scientists process it into full-color images.

The colors we see in Webb’s pictures aren’t what the camera “sees” directly. Because infrared light is invisible, scientists assign colors to different wavelengths to help us understand what’s in the image. These processed images help show the structure, age and composition of galaxies, stars and more.

By using a giant mirror to collect invisible infrared light and sending it to super-cold cameras, Webb lets us see galaxies that formed just after the universe began.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Adi Foord, Assistant Professor of Astronomy and Astrophysics, University of Maryland, Baltimore County

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

Why is the object of golf to play the least amount of golf? – Bryleigh, age 12, Chandler, Arizona

In most sports, the team or player with the highest score wins, and fans celebrate super-high-scoring games. In golf, it’s the opposite – the lowest score is the champion. And since golf scores are the number of strokes each player needs to get around the course, the object is to do it with as few strokes as possible.

I study sport management, which includes training people to manage golf courses, help run associations that set the rules, and create scoring for golf. When I play golf, I find that it’s a great mental test. If I score poorly on one hole, how do I play the next hole? Will I let frustration cause me to play poorly and score high again, or can I recover?

Skilled players are able to manage each shot, finding the best place to hit the ball so that they leverage the strengths of their game and work with conditions (weather, wind) at the hole they are playing. This allows them to limit the score they get on the hole.

In golf every shot is a stroke, and you play each hole only once. There are no do-overs or second chances, so each move is extremely important for scoring. That’s different from a game like basketball, where you may get a rebound or a second chance to make a particular shot.

Par for the course

Each hole on a golf course is assigned a par score, which is the number of shots the designer believes it will take to play that hole. Almost all golf courses are made up of par 3, par 4 and par 5 shots.

On a par 3, a person is expected to take three shots to put the ball in the hole. That usually begins with a tee shot from the starting point of the hole and then two shots around or on the green area where the hole is cut. Par 4s expect two shots, covering more ground, before they get to the green area; par 5s expect three shots.

Par is designed for each hole and then added up for the course. Most golf courses have 18 holes and a par between 70 and 72.

There also are par 3 courses, where every hole is a par 3, so they can be spaced more closely and players don’t have to hit long drives. And there are short courses with fewer than 18 holes and total pars as low as 27, usually set on smaller properties.

Golfers want their score to be at par, or even lower, for each course. A decent golfer would probably shoot around 90 on an 18-hole, par 72 course. Coming in close to par lets people play together and compete against each other. Imagine that they were all trying to use as many shots as possible: They would never finish a hole, let alone a full round of the course.

Each score is given a name in comparison to par for a given hole. A score two strokes under par is called an eagle, and a score of one under par is called a birdie. When players go over par, it’s a bogey for one stroke over, a double bogey for two strokes over, and so on. There also are less-known terms, such as a snowman, which is shooting an 8 on a hole.

Every shot matters

Other sports that reward the lowest scores or the fewest attempts include darts and pool. For example, in 8-ball or 9-ball pool, the winner is the first person who sinks all of their colors and either the 8 or 9 ball into pockets with the fewest shots. Similarly, both swimming and track and field are won with low scores, although these are based on competitors’ times, not strokes or shots.

Golf requires great concentration and a good understanding of how your shot may move in the air. Players also need strategies for getting around objects in front of them on the course, such as trees, ponds and sand traps, which are also known as bunkers.

Good golfers are able to control relatively closely where their ball lands. But one of my favorite statistics is that the very best professional golfers land their ball within 10 feet of the hole just 1 in 4 times when they hit from 100 yards away.

A sense of humor helps. Baseball great Hank Aaron once said, “It took me 17 years to get 3,000 hits in baseball. It took one afternoon on the golf course.”

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Patrick Tutka, Clinical Associate Professor of Health and Kinesiology, Purdue University

This article is republished from The Conversation under a Creative Commons license. Read the original article.