Tag Archives: planets

Space Day: Structure of the Planets

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This year for Space Day, Earth Science student, Jade, explains all about the structure of the sun, moon and the planets in the solar system.

The Sun

  • The sun isn’t a planet, it’s a star in the Yellow Dwarf stage of its life.
  • The sun is in the middle of the solar system and is a ball of hot gases (mostly helium).
  • Even though it is made of gases it still has 6 layers within it:
    • Core – Where solar energy is generated which is where the heat comes from.
    • Radioactive zone
    • Convection zone – Where the heat travels up to the surface.
    • Photosphere – Visible surface
    • Chromosphere – Thin layer of gas
    • Corona – Thick atmosphere extending for millions of miles and it’s only visible during a solar eclipse

Mercury

  • Mercury is the smallest planet in the solar system.
  • It experiences extreme temperatures, both hot and cold. The heat is from being so close to the sun and the cold is due to the lack of atmosphere which causes the heat to escape.
  • Mercury’s interior is made up of a solid inner core, liquid middle core and a solid layer of iron sulphides. Then there is a mantle and a crust which together are around 400km thick at and mostly made from silicate minerals.
  • On the surface it has craters from meteorite impacts and lava plains from past volcanism that ended around 750 million years ago.
  • Although it has extreme heat there is ice at the poles, even during the heat as the ice is in the shadows of craters.

Venus

  • Second closet planet to the sun.
  • It has an iron core, a rocky mantle and a thin crust, similar to Earth.
  • As the rocky mantle moves underneath the crust it bulges and forms mountains and volcanoes.
  • There isn’t any water on Venus due to its high temperature.
  • It has an atmosphere mostly made up of Carbon Dioxide, but it doesn’t have any wind due to its slow rotation.
  • It can sometimes rain sulfuric acid.

Earth

  • Solid inner core made of iron and nickel.
  • Liquid outer core also made out of iron and nickel.
  • Rocky mantle which is mostly a fluid which convects heat from the core to the surface. As it convects, it forces the plates of the crust to move around forming mountains and volcanoes as they collide or move away from each other.
  • The crust made up mostly of silicon and oxygen (the crust is thinner under the ocean than the rest of the crust).

The Moon

  • Similar to Earth in composition but no longer has volcanism as there are no plate tectonics.
  • The composition is so similar because they were made from the collision between a small planet and the Earth and the moon was the bit left over.
Mars

Mars

  • Mars has a solid inner core made of dense iron, nickel and sulphur.
  • It has a rocky mantle and a crust mostly made of iron, magnesium and aluminium.
  • Previously it had tectonics which formed volcanoes and the largest canyon in the solar system (Valles Marineris).
  •  It also has similar sedimentary processes to Earth such as dunes.

Jupiter

  • One of the gas giants mainly made up of hydrogen and helium.
  • Structure similar to the sun. It is unclear what the core of Jupiter is made up of, but it is surrounded by metallic hydrogen formed when the hydrogen is under so much pressure that the electrons are squeezed off making it electrically conductive like metal. The upper layers of Jupiter are then more hydrogen either as a liquid or gas (the high pressure and high temperature makes the hydrogen a liquid).
  • Jupiter spins so fast that it generates a magnetic field.
  • It has 63 moons, one of which is Europa:

Europa (a moon of Jupiter)

Europa has an iron core, a rocky mantle, an ocean of salty water, and a lot of ice.  

Saturn

  • Another gas giant mostly made of helium and hydrogen.
  • Saturn’s core is made up of dense metals like iron and nickel and some rocky material.
  • Saturn’s density is less than water which means it could theoretically float on a giant mass of water.
  • Saturn is the only one of the gas giants with visible rings as the rings are mostly made of ice which reflects the light well.

Uranus

  • This ice giant rotates at nearly 90o from the plane of its orbit, which makes it look like it’s spinning on its side.
  • The icy mantle surrounding the small rocky core is made up of dense water, methane and ammonia.
  • The atmosphere is made up of methane gas which give Uranus it’s blue-green colour.
  • It’s bigger than Neptune but it has a smaller mass.
  • It has 27 moons.

Neptune

  • Neptune is shrinking and releasing heat.
  • It has a similar structure to Uranus as its mostly made up of icy materials made of dense water, methane and ammonia fluids around a small rocky core.
  • It’s atmosphere is mostly made form hydrogen, helium, and methane and it doesn’t have a solid surface (similar to all of the gas giants.)
  • It has 14 moons.

STEM Students Answer Children’s Questions #1

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When visiting schools and museums our Street Scientists often get asked a variety of questions from curious children. Here are the answers to some of our favourite questions!

This week, we’re focusing on questions around Earth Science and other planets.

If the Earth is the right distance away for it to be not too hot, not too cold, how come the north and south pole are cold?

– asked by a student from Blaydon West Primary School

As the Earth goes around the Sun it spins on its own axis. The equator is the closest bit to the sun during the day so it heats up, and stays relatively warm during the night as the atmosphere is good at retaining heat. The poles however are always the furthest part away from the Sun hence never warm up and are thus are the coldest parts of the Earth.
– Leo, Mechanical Engineering Student

How do we get seasons?

– asked by a student from Blaydon West Primary School

The Earth’s axis of rotation is tilted by 23.5 degrees and so some bits of the Earth’s surface are slightly closer to the Sun than the other bits. So in the Summer, the Northern Hemisphere is angled towards the Sun; in the Winter it is angled away from the Sun.
– Leo, Mechanical Engineering Student

What are the rings of a planet made of?

– asked by a student from Mortimer Primary School

There are rings around all of the planets known as gas giants; Saturn, Jupiter, Uranus and Neptune. These rings are made up of asteroid and ice particles. Only the rings around Saturn can be seen from Earth as they contain more ice which reflects the sunlight more. The rings around most of the gas giants (Jupiter, Uranus and Neptune) were formed from the impact of asteroids and meteorites which threw dust out into orbit. Whereas Saturn’s rings were formed by the impact of an icy moon causing a lot of bigger chunks of debris to be thrown into orbit. Although the debris is pushing away from the planet the gravity pulls this debris towards the planet enough to keep it in orbit.
– Jade, Earth Science student

How do you make a planet?

– asked by a student from Bede Burn Primary School

All matter was formed in a huge explosion called the Big Bang over 13 billion years ago. There are two main theories about the formation of planets, but they are both driven by a force called gravity which is the force that keeps us on the ground and causes objects to fall when dropped. Gravity causes the material formed in the big bang to come together forming asteroids and eventually planets. As these asteroids crash into each other they release a lot of heat that causes them to melt. This melting allows the heavier, denser elements to sink to the centre of the planet and the lighter elements rise further up. This separation forms the layers within the planets.
– Jade, Earth Science student

Have any more questions you’d like to ask our experts? Write them in the comments below!

Exoplanet discovery

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Recently NASA have found the TRAPPIST-1 Solar System (named after the TRAnsmitting Planets and Plantisemals I Small Telescope). It is 40 light years away in the constellation of Aquarius and has seven Earth size Exoplanets (planets that orbit a star that isn’t the Sun) that have the potential to support life.

This is a big discovery as it is the largest amount of Earth sized planets ever found around a single star and it might help in the search for life on other planets. trappist

How did they find the TRAPPIST-1 Solar System?

  • The Star in the centre of the solar system glows brightest in infra-red light which can’t be detected by the human eye
  • The infra red light was detected by an infra red telescope called the Spitzer. This telescope is in space and follows the orbit of the Earth.
  • The radiation (light) detected from the TRAPPIST-1 star would periodically dim and then brighten again; this could show that a planet could be passing in front of the star.
  • The dips in light were not always the same amount, showing that there were actually seven exoplanets orbiting the star.
  • NASA used the dips in radiation to calculate the size of each planet in the solar system.
  • Space in between the dips in radiation means they can work out how it takes for a planet to orbit the star.
  • The planets were found to be very close together with orbits that interfere with each other due to gravity.
  • They used the estimated size of the planets to work out what the density of each planet is, to work out what the planet might be made of.
  • All seven planets may be suitable of supporting liquid water, with three in the habitable zone capable of having oceans.

spitzer
The Spitzer Telescope

What next?

It’s really rare to find this many planets that may support life in one solar system so its important to find out more about them. NASA are going to use transmission spectroscopy to study the composition of the seven exoplanets. This is a technique that gives information about the chemical composition of a planet and whether a planet has an atmosphere.

They are using more telescopes to study some of the other ultracool dwarf stars (like TRAPPIST-1), to see if they also have exoplanets that could support life.