This planet, HD 189733b, is the first exoplanet to have its color confirmed. We now know it is a deep, dark blue from a technique called secondary eclipse that scientists used to determine its albedo. As the planet was just about to finish transiting its host star relative to us, scientists measured light emission wavelengths and compared them to those of the star alone. It revealed a deep blue color “quite distinct from the atmosphere colors seen in our solar system.” Scientific American.
However, unlike the Earth and its blue oceans, the coloration of this planet, which lies 63 light years away from Earth, is due to clouds laced with silicate particles. This planet is a hot Jupiter, orbiting its host star in 2.2 days, tidally locking one side of it to be forever in darkness and the other forever in light. The temperature would thus be an average of 1,000 degrees Celsius, based on observations, and a temperature difference between near and far sides of 260 Celsius. This could fuel winds up to 8,700 kph littered with glass. Silicates condense at temperatures above 1300 Celsius, so this planet likely has ripping winds with shards of glass embedded in it. This example shows just how varied and extreme worlds can be in the universe. Nature sometimes stretches the human imagination and renders science fact more strange than science fantasy. Glass Rain.
Most people have New Years goals of going to the gym more or spending more time with their family. The New Horizons team had a New Years goal to capture a clear image of Ultima Thule, the furthest known Kuiper belt object at that time, on a New Years flyby. Most people will look at a picture of Ultima Thule and think that it is just two rocks conjoined together. To astronomers, being able to capture this picture was a historic moment in history.
Ultima Thule’s appearance didn’t resemble any of the other Kuiper belt objects. Once the pictures made it back to Earth, it was classified as a contact binary that consists of two spheres that are connected. The larger sphere is called Ultima, while the smaller sphere is called Thule. What makes Ultima Thule so special is that it shows a snapshot of the beginning of planetary formation. By studying Ultima Thule, astronomers have been able to gain valuable insight into how planets form in both our own solar system and other distant ones.
In a system 218 light years from Earth, scientists have discovered two planets, Kepler-138 c and Kepler-138 d, which make Earth look like a desert in comparison. Both planets were initially thought by scientists to be rocky super-Earths. However, after closer examination by the Hubble Space Telescope, scientists were able to determine that both planets are three times the volume of Earth, but only twice the mass. Although there are alternative explanations, the most likely one is that 50% of their mass is water. In comparison, the Earth’s mass is only 0.02% water. Source.
This was ascertained by the planet’s higher density than elements like gaseous hydrogen or helium, yet lower than a density equivalent to rock. However, the proximity to their host red dwarf star increases the predicted surface temperature of the planet. Since the presence of an atmosphere is likely with such an abundance of surface water, the planets probably have a thick atmosphere of steam with a water ocean beneath this atmosphere. The ocean might even have strange properties due to a combination of high pressure and high temperature. The most stunning prediction was an average ocean depth before reaching rock of 1,243 miles. Earth’s average ocean depth is around 2 miles. Source 2.
The significance of this discovery is obviously the likely presence of liquid surface water on an exoplanet’s surface. However, it also has implications for planetary formation models which show waterworlds only forming as ice worlds like Europa. This lends credence to the idea of planetary migration. It also opens scientists’ eyes to new possibilities of conditions on exotic, strange new worlds and the potential widening of human knowledge by continuing the hunt for new exoplanets.
Saying the universe is incomprehensibly massive, so much so only the brightest and closest objects and phenomena are visible to the naked eye. Throughout history people have had work arounds, be it using devices to mark inclination of stars to focusing light through telescopes to make the faintest bodies visible. One of the most interesting developments in observational astronomy would be the development of interferometry.
To explain how interferometry works, first let’s explain how light moves through space. Light is traditionally made through the vibrations of charged particles, giving it the form of a wave. Scientists knew this since the 17th century, however the issue is that most waves as they know it as a medium. A popular theory behind this medium in the 20th century would be the luminiferous aether, which physicist Albert A. Michelson and Edward W. Morley in attempted to study in the Michelson Morley Experiment. While the experiment failed in determining anything about aether, it show that light can undergo interference. The results of this experiment were also some of the key stepping stones to special relativity helping explain how light does permeate through space
The above shows how a general interferometer is made. The coherent light source emits light that all have the same wavelength and phase. Through the mirror some fraction of the light is deflected while some pass through. Eventually both divided streams of light reconvene at the detector. However, since both streams of light have travelled a different distance so they may no longer be in the same phase anymore. So initially the wave may have looked like this:
But now recombined they look like this (Each wave has half the amplitude as the one above):
Or in more extreme cases:
This shift net visible light being dampened when compared to the initial intensity. This is similar to if you end up pushing on a swing while the chair is still moving towards you. This shift is proportional to how much distance the two streams travelled compared to each other and is incredibly sensitive. This sensitivity allows for the observation of very minute phenomena.
LIGO the primary detector of gravitational waves uses this exact method to detect them. Through mirrors that are 4km apart to reduce outside interference slight disturbances in space caused by gravitational waves can be detected through the interference of light and measuring the intensity of the interference as a function of time can show how much the wave strains space over time.
Interferometers can also be used to amplify light as well, since if two separate locations were to gather light of the same wavelength, then corrected the phase shift and combine the information, that basically turns an array of smaller telescopes into one very power lens able to render images of the farthest corners of the universe. This technique is how the picture of Sagittarius A*, the blackhole at the center of the milky way, was taken,;which can be seen below.
Even at our limited resources and perspective, through the application of physics and mathematics into advanced instruments the universe ends up looking far brighter than ever before.
Super Earth CoRoT-7b next to Earth and Neptune for comparison, Source: Science News, Wikipedia
The planets of the solar system, and the categories they fall into is basically common knowledge in this day and age. There are the rocky and dwarf worlds with a mass and size comparable or less than that of Earths. These planets can be anywhere from close to the sun, far out at the edge of the solar system, or somewhere in-between. Then after these earth like worlds comes the massive ice and gas giants being 10s to 100s of times more massive and large than Earth. Such a large jump is a bit strange, since there should not be anything particularly wrong with a planet between the mass of Earth and Neptune, so is there anything that fits into that gap?
It just so happens that the answer to this question is a bit outside the solar system, specifically Exoplanets, which host worlds completely foreign to our perception of planets. It just so happens that one of there is a celestial body that happens to fit right into that large mass gap, they’re known as “Super Earths”.
Orbiting at a mass between 2 to 10 times that of earth, Super Earths are a very mysterious object since they actually encompass a large array of planetary compositions. Those with lower masses tend to be similar to earth with a somewhat thicker atmosphere. However as they get more massive that atmosphere eventually makes them similar to Neptune, those variety are normally called Mini Neptunes. Somewhere in-between these two lies some interesting possibilities such as water worlds, planets that consist mostly of water in a supercritical state (The line between liquid and gas) due to balancing both heating from their star, and pressure accumulated from the mass. The final product is a planet with a layer of water vapor on top of highly pressurized water surface.
Super Earths were first discovered in 1992 by Aleksander Wolszczan and Dale Frail orbiting a pulsar, a fast spinning and radiating neutron star, which showed that these bodies did exist. However, it was not until 2005 though that these bodies were found in something akin to solar system orbiting the red dwarf Gliese 876. Over the past couple years many more of these worlds were found, projected to take up 1/3rd of all exoplanets. These planets are also potentially quite livable, since these planets have been found within the habitable zone of stars such as Gliese 581, thus possessing the likelihood of having liquid water on the surface.
It must be known though that many of the details regarding the surface of these worlds is still a mystery. The Super Earth’s above found in the habitable zone can have a surface temperature ranging from -3to 40ºC depending on how much energy the planet’s surface absorbs. Even worlds that we’ve analyzed such as 55 Cancri e experience a temperature fluctuation of 1300ºC during a rotational period. Despite this uncertainty, Super Earths are considered one of the prime candidates of extraterrestrial life since their mass gives them a thick atmospheres, geologic activity and strong magnetic field, all conditions necessary to start life on earth.
Observing Super Earths have taught us so much about planetary formation, and hint at the possibility of life on other worlds, to a degree that the solar system simply can’t. Studying these far-out worlds are essential in fully understanding where and how we came to be.
Comets are characterized by their highly eccentric orbits and incredibly long periods. Comet Swift-Tuttle, for example, has an orbital period of 133 years. This is comparable to the orbital period of the furthest planet from the Sun, Neptune, which has a period of 165 years. From our perspective on Earth, 150 years is a long time. However, despite its seemingly incredibly long period, Swift-Tuttle is classified as a short period comet. Other short period comets include Halley’s Comet (~75 years) and Comet Encke (~3 years) Comets which truly take ages to orbit the sun are classified as long period comets, and can have periods ranging from 200 years to millions of years. The comet with the longest known period is C/2012 S4. It is classified as a “near-parabolic” comet due to having an eccentricity over 0.99, and its period is ~126 million years. While short period comets reside close to the solar system, sometimes even closer than Jupiter, long period comets like C/2012 S4 can be found far beyond the Kuiper belt. Long period comets are theorized to originate from the Oort cloud and may have been knocked out of the Oort cloud by the gravitational influences of passing stars.
Have you ever wondered why Jupiter looks so colorful? Well look no further than Jupiter’s
atmosphere, where you’ll find similar and yet different features from Earth’s own atmosphere. Jupiter’s atmosphere consists of the thermosphere, stratosphere, and the troposphere, much like Earth’s atmosphere, yet where they differ is what each layer consists of. Jupiter’s thermosphere is heated by solar x-rays and Jupiter’s own magnetosphere, Jupiter’s stratosphere absorbs ultraviolet light not with oxygen and ozone like Earth, but with other particles, and Jupiter’s troposphere is where Jupiter gets its colors from. Jupiter’s troposphere consists of ammonia, ammonium hydrosulfide, and water, and as you go further up into the troposphere, the temperature gets colder and colder, so water condenses first, then ammonium hydrosulfide, then ammonium. Water and ammonia clouds are white, but ammonium hydrosulfide reflects brown and red light, giving Jupiter its distinctive colors.
Today I wanted to talk about one of the most fascinating moons in the Solar System, Io is one of the four Galilean moons that orbits Jupiter, which are each large enough to be counted as planets or dwarf planets if they orbited the Sun. Io is covered in snow, and yet is by far the most volcanically active world in our solar system. There is not a single impact crater on Io’s young surface because of how geologically active it is. You would think that Io would have ceased geological activity long ago because of how small it is, but its interior is being heated up through a process called tidal heating. Jupiter exerts a tidal force on Io similar to how Earth exerts a tidal force on the Moon, but because Jupiter is so much larger, the tidal force causes Io to be stretched like Silly Putty which creates friction and heat.
Saturn V the moon, also known as Rhea, is the second largest moon of Saturn. But Saturn V, the rocket used in the Apollo missions, is one of the largest rockets ever built by mankind. NASA’s Saturn V is the largest rocket in the Saturn family and was used in 9 Apollo missions to carry humans to lunar orbit, and was used to launch the first US space station, Skylab in 1973.
Saturn V has three stages, and the “V” in Saturn V refers to the five powerful F-1 rocket engines in the first stage of the rocket. These engines burn kerosene and liquid oxygen to provide the initial thrust, carrying the 3000-ton rocket to nearly 3 km/s. The second and third stages burns liquid hydrogen and liquid oxygen in smaller but more efficient J-2 engines. After discarding the first stage, the second stage propels the craft to 25000 km/h, close to the orbital velocity, and almost brings the craft to LEO. To ensure the safety of the astronauts and continuous functionality even in event of system failure, Saturn V was tested extensively and equipped with redundant systems. Such measures proved useful when Apollo 12 remained intact and functional though being struck twice by lightning.
Saturn V’s successful launches included the crewed flights of Apollo 8-17. I would consider Apollo 13 successful for Saturn V itself, since the problem was mainly on the oxygen tanks of the service module. The uncrewed flights Apollo 4 and the launch of Skylab were also successful (uncrewed Apollo 6 experienced engine failure in stage 2). The launches of Saturn V are shown below. Note that the rocket for Skylab did not have an escape tower (a launch escape system that would carry the manned module away in event of sever rocket failure).
Until today, Saturn V remained the only rocket that carried humans beyond Low Earth Orbit, and it is amazing considering that these brilliant engineers and scientists managed to accomplish this 50 years ago.
Many space missions are aimed outwards, away from the center of our solar system into the deep unknown. Fewer are aimed inwards, because what else is there to explore? The Sun is a fiery ball of extraordinary mass that we likely have no hope of making contact with soon, but how close can we get? The Installation of the heat shield
The spacecraft works in tandem with other orbiters such as BepiColombo and STEREO-A to understand the evolution of solar wind as it travels through space. It recently completed its fifteenth close approach to the Sun. It is hoped that the PSP can help us better understand solar weather, which has adverse effects on satellites and electronics, and also why the corona is substantially hotter than the photosphere.
