This newly processed image of Europa shows - in great detail - the cracks and fractures along the surface of Europa.
Europa’s surface is dynamic, constantly changing. It gets torn apart by tidal forces, and geysers of water fire up and over the fractures they came from - only to land and form a fresh layer of water ice.
This same pulling and pushing of Europa generates immense amounts of friction and therefore heat.
Below the icy surface - Europa has an ocean of liquid water: possibly more water than there is on Earth.
In that ocean… we hope to find out. NASA proposed a mission called the “Europa Clipper” to orbit Jupiter in order to perform numerous flybys of the icy world.
The Clipper is hoped to be followed by an orbiter and a lander, all designed to explore the habitability of Europa’s ocean.
It may be the best candidate for extraterrestrial life in our solar system
The moon is the easiest celestial object to find in the night sky — when it’s there. Earth’s only natural satellite hovers above us bright and round until it seemingly disappears for a few nights. The rhythm of the moon’s phases has guided humanity for millennia — for instance, calendar months are roughly equal to the time it takes to go from one full moon to the next.
Moon phases and the moon’s orbit are mysteries to many. For example, the moon always shows us the same face. That happens because it takes 27.3 days both to rotate on its axis and to orbit Earth. We see either the full moon, half moon or no moon (new moon) because the moon reflects sunlight. How much of it we see depends on the moon’s position in relation to Earth and the sun.
Though a satellite of Earth, the moon, with a diameter of about 2,159 miles (3,475 kilometers), is bigger than Pluto. (Four other moons in our solar system are even bigger.). The moon is a bit more than one-fourth (27 percent) the size of Earth, a much smaller ratio (1:4) than any other planets and their moons. This means the moon has a great effect on the planet and very possibly is what makes life on Earth possible.
After getting this cardigan I thought how funny it is how we see stars as tiny dots and depict them cute like that while they’re actually massive spheres of plasma with nuclear fusion reactions taking place inside their cores. Ah, the vantage point.
Obscuring the rich starfields of northern Cygnus, dark nebula LDN 988 lies near the center of this cosmic skyscape. Composed with telescope and camera, the scene is some 2 degrees across. That corresponds to 70 light-years at the estimated 2,000 light-year distance of LDN 988.[2400x1800]
Far away there’s a massive planet made of ice, orbiting a small, dim red star. This planet is so close to its star that it’s burning at 800˚ F. A planet of burning ice…
…around another star there orbits a huge, Earth-like world. It’s in the perfect spot - the “Goldilocks Zone” of it’s star where any water on the planet would be in liquid form… an oasis amongst the eternal darkness of space.
When you consider the vast distance between us and these strange worlds, do you ever wonder how we can possibly find and learn more about them?
These are the three main ways we hunt exoplanets:
Method #1: The Transiting Method
We can measure a foreign star and record how bright it is. If and when a planet orbits past its star, there will be a drop in brightness, the same way the Moon eclipses our Sun.
A special property of light and quantum mechanics allows us to study the light that passes through an exoplanet’s atmosphere. Signature changes in the starlight give us clues as to what material the atmosphere contains (methane, nitrogen, water vapor, oxygen etc.).
The time it takes for a planet to orbit across the face of its star tells us how far away it is from its planet. If we detect water vapor and it orbits its star at the right speed (thus from the right distance) we can get a good idea of which planets might have oceans of liquid water.
The size of the planet can be determined by how much starlight it blocks.
Method #2: The Wobble Method
Newton found out (and expressed in his third law of motion) that when an object exerts a force on something, an equal and opposite force is exerted back.
When a star swings planets around it via its gravitational pull, those planets exert the same amount of gravitational force back on their star. The star better resists the pull because of it’s much greater mass.
It doesn’t, however, remain uneffected: A star with planets is pulled by these planets so that it wobbles around the center of mass of their solar system.
By measuring patterns in wobbles we can measure how many planets are orbiting around a star, how far they are (an approximation) and their mass.
Method #3: Direct Imaging
Light behaves in strange ways. Like a particle and like a wave. Some wavelengths shred our DNA and kill us. Some keep us warm. Some of it allows us to see. We use radio-length waves to communicate wirelessly…
When a planet orbits around a star, trying to detect reflected and emitted light from the planet can be extraordinarily hard. A star vastly outshines a planet.
So how could we possibly photograph planets directly?
This is largely a technique still being developed. Sometimes chance positions relative to each other allow us to detect planets directly but soon we’ll be able to photograph planets in some detail - at will.
Star shades are one strategy. The way light diffracts around corners makes it a strange and slippery thing to handle - it does work predictably however. The star shades are designed so that the light from a target star will diffract away from out camera apertures and the light from the planets will be directed through them.
Several space telescopes are being launched in the next decade that will be equipped with technology to allow for direct photography of exoplanets.