Exoplanets 101: Does the earth have a twin?

potential habitatable planets

Potential Habitable Planets

An extrasolar planet is a planet that orbits a star that’s not our sun. Even though these planets can be recognized, and their sizes measured, they are light years away so it would take astronomers thousands of years to reach these extrasolar planets. To detect these planets, scientists use either one of two methods: doppler and transit.

The doppler method measures the star’s wobble. The wobble is caused by the force of gravity from exoplanets themselves, pulling the stars in different directions during their orbits. Measuring the wobble also makes it possible for astronomers to measure the planet’s mass. The greater the wobble of the star, the greater the mass of the exoplanet.

The transit method: after observing a star over a period of time, astronomers sometimes notice a faint dimming of its light. This dimming is probably caused by a planet orbiting past it. Taking note of the “size of the dim” through the transit method gives away the size of the planet. The doppler technique gives astronomers the mass of the exoplanet, and the transit method gives them the radius/physical size.

Combining the results, astronomers are able to calculate the density of the exoplanet. The value of the density of the planet is then used to determine the kind of planet that has been discovered. Ie, is it a rocky planet like earth or a gaseous, giant planet like Jupiter? A gas giant like Jupiter has a low density, and a rocky metallic planet like earth has a high density.

What will it take to find a planet like earth? There is a difference between being earth-sized and being earth-like. Astronomers have discovered hundreds of planets that may be the same size as our earth but a planet must be at the right distance from its  star, to have the right conditions where liquid water could exist on its surface. We are not entirely sure of what the atmospheres on these earth-like planets may be like, or whether these earth-like planets actually have atmospheres but we are excited to discover what could be our very own twin planet!

The Sun – the heart of our solar system

the sunn

Planetary System

The star at the center of the solar system plays a special role for us here on earth. It was formed about 4.5 billion years ago, in the Orion spur (in the milky way galaxy). It was born from the collapse of a cloud and dust called the “solar nebula”. It then condensed into a burning ball of gas, called the sun.

What makes the sun the heart of our solar system?

  1. Its magnetic field
  2. Its gravitational pull.

The sun’s magnetic and gravitational impacts are largely due to its size. It is large enough to hold the solar system intact, it is about 100 earths wide, and it could theoretically fit all 8 planets nearly 600 times. Additionally, it contains about 99.8% of all the mass in the solar system.

If you are guessing that this is why planetary bodies orbit it, you are right. Because of its mass, it has a great pull on the fabric of space, creating a gravitational force that causes nearby bodies to be drawn towards it. Without this pull, the other planets will vanish into deep space.

The magnetic field of the sun is called the heliosphere, and it encapsulates the entire solar system. It protects the planets form harmful cosmic radiation. It is caused by the sun’s plasma, and it causes the pushing of particles towards its poles.

Will the sun last forever? Unfortunately not. It is expected to collapse into a white dwarf in about 6.5 billion years, after it runs out of its hydrogen fuel. That’s such a depressing thought. I hate to imagine what will happen to our existence as a result of this. Maybe we should think of ways to refuel the sun? Or maybe we should just refrain from worrying about things we cannot change. In the meantime, let’s enjoy the sun’s magnetic field, gravitational pull and vast amounts of energy.

Radioactivity 101. Is the sun radioactive?

sun radio

sun spots and solar flares

Chemical reactions occur because atoms strive for stability. Just like the outer electrons require a certain number of electrons to become stable, the nucleus requires a certain number of protons and neutrons to achieve this stability. The decomposition (breaking down) of the nucleus to achieve this stability is what we call Radioactive Decay. An unstable nucleus can be referred to as a Radionuclide.

Why do atoms decay in the first place? Each nucleus contains protons and neutrons. If there are too many or too few of the neutrons, the core of the atom becomes unstable, leading to the decay of the radionuclide. 

How do we measure the rate of decay? We measure this by measuring the time it takes for exactly one-half of the radioactive substance’s nucleus to decay.  There are three types of decay, and each one is based off the radiation emitted through radioactivity. The three types are: alpha, beta or gamma decay. Our very own sun emits gamma rays, but unlike that of unstable nuclei, its rays are from solar flares.