Worlds Beyond Our Own
- 6th Nov 2025
- Author: Caitlin Hauxwell
In our local skies, eight planets orbit a star in the patch of space we call the Solar System. Four of these planets are rocky, two are gas giants, and two are ice giants. Jupiter has storms which last centuries. Venus has atmospheric pressures that could crush a nuclear submarine. Earth has life.
But our Universe extends infinitely beyond this, with at least 100 billion stars in our galaxy alone and even more planets scattered around them. These planets – ones beyond our solar system – are called exoplanets. And with the variety already observed in our close galactic neighbourhood, it’s no wonder we’ve found some exoplanets hotter than stars, others massive enough to pull pulsars off kilter, and even worlds with weather patterns so extreme they belong firmly in science fiction.
The Origin Story
First, however, let’s go back to the beginning of exoplanet hunting.
Even though ideas theorising the existence of other worlds in the heavens have been present since at least the time of the Ancient Greeks, the science of searching for them remains a relatively recent field. You see, space is big!
It can be incredibly difficult to spot something as “small” (on cosmic scales) as a planet, even on our own doorstep. Neptune, for example, was only added to our Solar System records in 1846 – and Pluto (although no longer a planet) almost 100 years after that!
Despite scientists assuming planets must orbit many of the countless stars we see in the night sky, it wasn’t until 1992 that we confirmed this for sure (ironically, orbiting a star that was never visible to our naked eye in the first place).
This came from one particularly serendipitous observation - a slight wobble in the periodic flashing of a big space “lighthouse” (a pulsar) caused by the strong gravity forces of two massive orbiting exoplanets. These two worlds, Phobetor and Poltergeist, would go on to open the floodgates for an unprecedented race to uncover more of this hidden aspect of the Universe.
The Scientific Intrigue
“Pulsar timing” may have been our first successful exoplanet hunting method, but we’ve since developed a whole array of techniques in our toolbox as technology has improved.
Nowadays, we can hunt for these worlds by looking at the small dips in starlight produced when they pass in between us and their host stars or when the tugging of their gravity changes the speed of that star. Another method involves when a planet’s gravity bends light in just the right way that it’s focused perfectly onto our detectors. And we can even capture exoplanets directly in photos taken by powerful telescopes.
Let’s jump, then, thirty years ahead from Phobetor and Poltergeist as NASA officially confirms the existence of 6,000 discovered exoplanets. Scientists are no longer happy with just finding these new worlds – it’s about uncovering what the strange surfaces beneath thick, swirling atmospheres and shadow-covered faces might look like.
Modern Exoplanet Hunting
By analysing the spectrum of light that arrives at our eyes from space, we can deduce all sorts about the atoms and molecules that this light passed when travelling through the atmosphere of a distant planet. Called spectroscopy, we’ve used this technique to find planets covered in oceans that are thousands of miles deep, puffy planets with the likeness of a toasted marshmallow, and potential planets with cores of pure diamond.
Combining what we know about a planet’s composition with its proximity to the “Goldilocks Zone” (not too close or hot and not too far or cold) around its star, scientists can put together an ever-growing list of planets not too dissimilar to Earth – planets which may have liquid water and thick, nitrogen-rich atmospheres. While these may be a good destination for your next cosmic camping holiday, I want to introduce you to some weird and wonderful worlds you might want to prepare for a bit more before you visit…
Three Wacky Worlds: A Visitor’s Guide
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![Artist’s rendition of HD 189733b]()
NASA You Can Stand under My Umbrella
If you’ve ever been caught in a strong hailstorm, you’ll know it’s not for the faint of heart. But on HD 189733b, a little icy patter on your face would be the least of your worries. Despite its scorching hot atmosphere and 5,000mph winds, it’s the shards of hailing molten glass you’ve got to look out for here. Whipped up and launched sideways at any unsuspecting visitor, this terrifying forecast is made no better by the toxic gas in the air! Not the kind of rain you’d want to sing in.
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![Artist’s rendition of KELT-9b and its host star]()
NASA It’s Getting Hot in Here
The highest temperature ever recorded on Earth of 56.7°C, occurred in the aptly-named Death Valley. The hottest planet in our Solar System, Venus, can reach almost ten times this heat. But exoplanet KELT-9b makes this all look like child’s play. With a maximum temperature of over 4,300°C, the hottest exoplanet ever discovered has conditions more extreme than many stars. Scorched by its own super-heated sun, this planet’s atmosphere is being boiled away at an alarming rate while molecules within it are ripped apart. And the bad news is that it’s only getting hotter!
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![Artist’s impression of super-Saturn J1407b]()
Ron Miller/NASA Put a Ring (or Several) on It
Saturn may be famous for its rings, but J1407b puts them to shame! If we put our star in place of this giant planet, its ring system would stretch almost all the way to Venus. That’s over 300 times wider than Saturn’s system. Criss-crossed by gaps and stripes that could even indicate the existence of moons orbiting this exoplanet, it’s safe to say that views from J1407b must be spectacular with meteor showers galore! Bring some hot chocolate and prepare to wish on a shooting star.
So, Are We Special?
The truth is, Earth-like planets orbiting Sun-like stars at the perfect distance with the perfect composition are going to be rare! Our thick, life-supporting atmosphere, climate of moderate extremes, Goldilocks distance from the Sun and vast oceans of liquid water is a perfect balance for nature to not just survive, but thrive.
Outside this, the Universe is the laboratory of a mad scientist – planets of every size, makeup, distance, and weather conditions exist everywhere we look. Despite this, our Solar System shares some features with many others out there – such as how our small rocky planets orbit close together like “peas-in-a-pod.”
Equally, however, single-star systems like our own seem to be in the minority, and it’s possible that binary sunsets (like those on Tatooine in the Sci-Fi realm of Star Wars!) may be common enough to make our own daytime view the rare one. Take Algol for instance, this binary star system that appears to wink as the two stars orbit each other. (Click the image to see the two stars in a cosmic dance).
Working out the exact rarity of our planet depends on who you ask and what you look at. To me, however, Earth continues to be the most incredible, beautiful, and perfectly unique planet to exist. Because no matter how far we look, scanning exoplanets large and small, hot and cold, bright and dark, near a far - we’ve yet to find anyone looking back.
Full references / credits:
(Banner) A collection of artists’ concepts of confirmed exoplanets. Credit: NASA’s Goddard Space Flight Center
(1) Artist interpretation of a pulsar with a planet. Credit: NASA/JPL-Caltech
(2) An artist’s rendering of an exoplanet seen from its moon. Credit: IAU / L. Calçada
(3) The Goldilocks Zone changes for different star systems. Credit: ESA
(4a) Artist’s rendition of HD 189733b. Credit: NASA
(4b) Artist’s rendition of KELT-9b and its host star. Credit: NASA
(4c) Artist’s impression of super-Saturn J1407b. Credit: Ron Miller/NASA
(5) Dr. Fabien Baron CC BY-SA 3.0 (https://en.wikipedia.org/wiki/Binary_star#/media/File:Algol_AB_movie_imaged_with_the_CHARA_interferometer_-_labeled.gif)
