Earlier on in this scorching July on planet Earth, scientists revealed that there is an ultra-hot exoplanet in the universe acting like a mirror.
The European Space Agency (ESA)'s CHaracterising ExOPlanet Satellite (Cheops) mission discovered the ultra-hot LTT 9779 b, an exoplanet orbiting a star about 262 light-years from Earth, with an albedo (reflectivity) of 80%. This makes it the shiniest exoplanet ever observed, surpassing even Venus, which has an albedo of 75% (thanks to its reflective cloud layer), and Earth with its 30% albedo.
Most planets have a low albedo, either because they have an atmosphere that absorbs a lot of light, or because their surface is dark or rough. The planet was first spotted by NASA's planet-hunting TESS mission in 2020, but it's only recently that ESA discovered how shiny it truly is.
A scientific paper describing the new research ("The extremely high albedo of LTT 9779 b revealed by CHEOPS: An ultrahot Neptune with a highly metallic atmosphere", 10 July 2023 – Download The_extremely_high_albedo_of_LTT 9779 b), and published in the journal Astronomy & Astrophysics, shed a light on the planet.
LTT 9779 b, a planet about the size of Neptune and five times the size of Earth, holds the title of being the largest "mirror" in the known Universe due to its highly reflective surface. Its remarkable reflectivity that makes it the shiniest planet outside our solar system is attributed to its unique metallic cloud cover, composed primarily of silicate and metals like titanium.
The planet's surprising reflectivity posed a puzzle initially, as its temperature reaches around 2,000° Celsius. Temperatures above 100° Celsius are too hot for water clouds to form. Therefore the planet shouldn't have any clouds. However, researchers likened the cloud formation to condensation in a bathroom after a hot shower, where oversaturation with silicate and metal vapors allows the formation of metallic clouds, even under such extreme heat and help the planet survive.
LTT 9779 b's uniqueness doesn't end there; its size and temperature classify it as an "ultra-hot Neptune," and it resides in what is known as the "hot Neptune desert." Planets of this size and mass are not typically found orbiting so close to their stars and they shouldn't exist as their atmosphere should be blown away by their star. All previously discovered planets that orbit their star in less than a day are either gas giants similar to Jupiter with a radius at least ten times larger than Earth's – or rocky planets smaller than two Earth radii. In this case the planet is a remarkable 4.7 times larger in radius and 29 times more massive than Earth, and a year on LTT 9779 b takes just 19 hours.
Yet, despite its extreme conditions, the planet does not evaporate probably because its metallic clouds play a crucial role in preventing it from getting too hot and help it to survive stopping the planet from being blown away by the star's intense radiation.
By utilizing Cheops' mission, scientists successfully examined the properties of LTT 9779 b through observations made when the exoplanet moved behind its host star. Typically, when an exoplanet orbits its star, its passage in front of the star causes a noticeable dimming of the star's light.
Surprisingly, a similar dimming effect occurs when the exoplanet moves behind the star. This phenomenon arises because, when the exoplanet is to either side of the star, the light it emits and reflects contributes to the overall brightness of the system, resulting in observable variations in the emitted light. This valuable data, combined with insights from other instruments, contributes significantly to our comprehensive understanding of this distant exoplanet.
So, why should we care about this planet in fashion? Well it's obvious: ultra-hot, reflective, metallic – there is enough to be inspired in these adjectives or in the words "exoplanet" and "albedo". They could help you coming up with ideas for clothes and accessories or to build an amazing narrative, a vision of a ultra-hot burning world with heavy clouds of metals floating aloft, raining down titanium droplets, that you could use as the mood for a runway show. Always remember that science is an friend and an ally for those fashion designer willing to delve into it; it is an endless source of inspiration and not an inscrutable and scary discipline.
Besides, the future of exoplanet research will be trending in the next few years: Cheops is indeed the first of a trio of dedicated exoplanet missions. Plato, launching in 2026, will focus on Earth-like planets in potentially habitable zones, while Ariel, set to join the fleet in 2029, will specialize in studying exoplanet atmospheres. These missions will open up new possibilities for exploring and understanding distant worlds beyond our solar system, so start studying them to create fashion collections that can go "to infinity and beyond"!