An exoplanet is a planet that is the brainchild of a distant star and is beyond our solar system. Some of these extraterrestrial worlds resemble the planets that inhabit our solar family, while others are so different that they are real “weirdos” – unlike anything astronomers have ever observed in our solar system. Pursuing distant alien worlds beyond our star, astronomers have come to the inevitable conclusion that planets can consist of almost anything. In December 2019, a team of astronomers announced the discovery of a completely new class of planets that had never looked like anything before. These eccentric “chubby” balls are inflated to such an extent that they are almost the size of Jupiter, but make up only 1/100 of its mass.
Mercury Venus, Earth and Mars – planets of the Earth group, inhabiting our solar system. On the contrary, the most massive quartet of outer planets, Jupiter and Saturn, are classified as gas giants. Uranus and Neptune, two of the most distant of the huge planets, differ in composition from gas giants and are classified as ice giants.
A quartet of planets of the Earth group, like our own Earth, are solid worlds consisting mainly of silicate rocks or metals. Four worlds bask in the warm, well-lit interior of our solar system and are relatively close to our sun. They are located between our rotating, smoldering star and the main asteroid belt between Mars and Jupiter.
A massive duo of gas giants, Jupiter and Saturn, is a gas-rich world consisting mainly of hydrogen and helium. Gas giants are sometimes referred to as “failed stars.” This is because they contain the same basic elements as the star.
In the 1990s, astronomers realized that Uranus and Neptune were indeed a separate class on the planet, unlike their two much larger gas brothers and sisters. This beautiful bluish duo is considered an ice giant.
The alien worlds of “sugar wool” are now called Super Puffs. These bloated planets may represent a short-term transition phase in the evolution of the planet. Because this phase is short, it may explain why astronomers don’t see anything like this in our solar system. It has been suggested that Super Puffs may have been born much further away from their stars and then migrated inward to the warmth and warmth of their star parents. At this point, their hydrogen and helium atmospheres of low density soar into the space between the planets. In the future, many small planets may be left to tell their stories.
Familiar planets of our star
As of December 1, 2019, there were 4,135 tested exoplanets inhabiting 3,073 systems, of which 673 had more than one single planet. Some of these planets are very similar to the famous family of large planets of our star, while others are so exotic that astronomers did not even dream that such worlds can exist – until they were discovered.
The three main classes of planets in our solar system are different from each other. The quartet of planets of the inner Earth has a hard surface, which strongly distinguishes them from the quartet of external gas planets – both two gas giants and two ice giants. The four largest outer planets contain a mixture of hydrogen, helium and water that exist in various physical states.
All the planets of the Earth group in our solar system have the same basic structure. This means that the four small rocky planets have a central metal core consisting mainly of iron, with the surrounding silicate mantle. The Earth’s moon is similar to the four main inner planets, but has a much smaller iron core.
In the early years of our solar system, when it was just forming, there were probably many more planets in the Earth’s population. However, it is believed that most of these ancient planets in the Earth group collided with each other and merged – or were unceremoniously banished from our solar system by the four existing planets of the Earth group.
Two heavily gas-covered striped giants, Jupiter and Saturn, are almost entirely composed of hydrogen and helium, with heavier atomic elements making up 3-13% in mass. It is believed that the two external gas giants of the solar system consist of an outer layer of molecular hydrogen surrounding a layer of metallic hydrogen. It is said that this massive duo also has the cores of molten rocks. The outer part of their hydrogen atmosphere consists of many visible cloud layers, consisting mainly of water and ammonia. The layer of metallic hydrogen makes up the bulk of each of the two planets and is called “metal” because very high pressure causes hydrogen to turn into an electric conductor. It is believed that the nuclei of this giant duo consist of heavier elements at such high temperatures that their properties are not fully understood.
Uranus and Neptune are two external giant planets, and they mostly consist of elements heavier than hydrogen and helium. In astrophysics and planetary science, the term “ice” refers to volatile chemicals with freezing temperatures above about 100 K, such as water, methane or ammonia, with freezing temperatures of 273. K, 91 K and 195 K. respectively.
The solid components of the two ice giants were probably already solid when they were incorporated into the duo during their formation either directly in the form of ice or trapped in water ice. Currently, very little water in Uranus and Neptune is in the form of ice. Instead, water usually exists as a supercritical liquid at temperatures and pressures inside the duo.
Ice giants consist only of 20% of hydrogen and helium by mass, unlike the gas giants of our solar system, Jupiter and Saturn, both of which contain more than 90% of hydrogen and helium.
Strange case of super Puff planets
Mysterious planets made of super puff plastic are sometimes called “sugar wool planets” because they are denser than cotton candy. New data from NASA’s Hubble Space Telescope (HST) has provided the first valuable clues to the chemical composition of a pair of these bloated planets in the Kepler 51 system. This particular system of exoplanets actually contains three superpuffs orbiting the young Sun. Star. The system itself was discovered in 2012 by NASA’s Kepler Space Telescope. Only in 2014 was established extremely low density of these exotic worlds “sugar wool” – much to the surprise of many planetary scientists.
Recent HST observations have allowed a team of astronomers to more accurately determine the size and mass of these planets, independently confirming their extremely low density, ‘bloated’ nature. Although these whimsical worlds of “sugar wool” are no more than several times the mass of our planet, their hydrogen and helium atmospheres are so bloated that they almost reach the size of the striped colossus of our own solar system, Jupiter. Despite the fact that the superfoods are almost gigantic in size, they are about a hundred times lighter in mass.
How and why the atmosphere of these exotic superclouds spreads outwards, it is unknown. However, their inflated atmosphere made them particularly interesting objects for further atmospheric research. Using HST, a team of astronomers searched for other clues and took a particular interest in detecting water in the atmospheres of planets called Kepler 51b and 51d. HST observed the planets as they passed (crossed) the radiant face of their parents. Scientists wanted to recognize the infrared color of their sunsets – thus determining the amount of light absorbed by the atmosphere into infrared light. This type of observation allows planetary experts to look for clicking signs of chemical components on the planet, such as water.