My Science School

The world beyond our own has always been a subject of curiosity and fascination. Space exploration projects over the years have succeeded in understanding the universe better. What are other planets in our solar system like? Do aliens realty exist? If so, where could they possibly live? These are some of the questions the projects have been constantly trying to seek answers to.

The Kepler Space Telescope was launched, in, 2009 to find answers to one such question, — how many earth-sized planets are there in the habitable zones of other stars in the Milky Way? The space observatory outlived its initial planned Lifetime of three-and-a-half years. It was retired, in October 2018. In its nine years of operation, Kepler discovered 2,662 planets and revealed, vital details about planetary systems.

Now, combing through data from Kepler, Michelle Kunivnoto, a PhD candidate of astronomy at the University of British Columbia, has discovered 17 new planets. This includes a potentially habitable Earth-sized world, named, KIC-7340288 b.

What are exoplanets?

On a clear night sky, you see thousands and thousands of stars. About 200 to 400 billion stars make up our galaxy, the Milky Way. We know quite a bit about Earth and other planets that orbit the Sun. Do other stars have planets orbiting them? Yes, they do. Astronomers have discovered about 3,694 such planets in more than 2,000 star systems since 1995.

These planets which are outside the solar system and orbiting a star are called exoplanets (extra+solar planets). There are also those that are outside a star system. They are called rogue exoplanets.

What do we know about KIC-7340288 b and other exoplanets discovered last month?

KIC-7340288 b, about 1,000 light-years away from, Earth, is in the habitable zone of its star. It is just one and a half times the size of Earth - small enough to be considered, rocky, instead of gaseous like the giant planets of the solar system.

A year on KIC-7340288 b has 142 days. It orbits its star at 0.444 Astronomical Units (AU, the distance between Earth and the Sun) - just bigger than Mercury's orbit in our solar system.

The planet gets about a third of the tight that Earth gets from the Sun.

Of the other 16 new planets discovered, the smallest is only two-thirds the size of Earth. It is one of the smallest planets to be found with Kepler so far.

Who is Michelle Kunimato?

Michelle Kunimoto is a doctoral candidate of astronomy at the University of British Columbia. This isn't the first time Kunimoto has discovered planets. She found four while she worked on her undergraduate degree.

How did Kepler detect planets?

When a planet passes in front of a star, the event is called a "transit. On Earth, we can observe an occasional Venus or Mercury transit. These are seen as a small black dot travelling across the Sun as the planet (Venus or Mercury) passes between the Sun and us, blocking sunlight. The Kepler detected planets using this transit method, that is, the telescope spotted planets by looking for tiny dips in the brightness of a star caused by the planets' transit.

Kepler first carried out its work by staring at more than 1,50,000 stars simultaneously. Once a planet is detected, its orbital size, temperature and the temperature of its parent star are calculated to find out if the planet is habitable.

The Kepler mission warranted that the stars be monitored and their brightness be measured continuously for transits. This meant that the Sun should not block the field of view of the telescope. Hence for the first four years, Kepler was pointed, to a field in the constellations of Cygnus, Lyra, and, Draco, which are well out of the ecliptic plane of the Sun.

What makes a planet habitable?

››Energy, carbon and Liquid water are the most important factors for Life to exist.

» Life possibility depends on whether the planet exists within the habitable zone. The habitable zone around a star is the range of distance within which temperatures allow water (essential for life) to remain Liquid on the surface of a planet.

» The host star should, be stable. Its Luminosity should not be too severe to burn up the planet.

» The planet must be made up of rocks, and not gases.

» It should not have a very tow mass. Low mass means Low gravity. Low gravity cannot retain atmosphere. Further, the atmosphere should have a protective Layer of essential gases.

» A rapidly rotating magnetic field to protect the planet from flares from nearby stars, is also vital.

What is the basis on which exoplanets are named?

Exoplanets orbiting a single star are christened by taking the name of the parent star and adding a tower case Letter to it. The first planet discovered in a system is given the designation "b” (the parent star is considered to be "a") and Later planets are given subsequent Letters.

 

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The International Space Station (ISS) is a habitable artificial satellite in low Earth orbit. A joint effort by participating space agencies, ISS serves as a space environment research laboratory. In terms of design, the ISS belongs to the third generation that allows modules to be added or removed from the existing structure, thereby allowing for greater flexibility.

The three generations

The first generation of space stations such as Soviet Union’s Salyut 1 and the U.S. Skylab had monolithic designs that consisted of one module with no resupply capability. The second generation of space stations, such as Soviet Union’s Salyut 6 and Salyut 7, consisted of a monolithic station, but with ports to allow resupply cargo spacecraft. The third generation, which are called modular space stations and now includes the ISS, correspond to those with more than one primary spacecraft that are launched independently and docked in space.

Soviet Union’s Mir space station marked the beginning of the third generation of space station design. The name “Mir” can be translated from Russian to mean “peace”, “world” or “village” – an apt choice for a space station that hosted people of various nationalities.

Different modules

On February 20, 1986, the assembly process began with the launch of Mir’s core module into orbit. Kvant 1 (1987), an astrophysics laboratory; Kvant 2 (1989), an augmentation module containing supplementary life-support equipment; Kristall (1990), a technology module that served as a materials-sciences lab; Spektr (1995), a power module that also allowed for remote observation of Earth’s environment; a docking module (1995); and Priroda (1996), Earth sensing module for experimenting with remote sensing; were the different modules launched and added to Mir over a decade.

Mir, however, started hosting humans even as more and more modules were added to it. Starting from March 1986, when the first crew docked with Mir, up until June 2000, when the last occupants left the space station, Mir received crew members from a number of expeditions. During its 15-year space flight, Mir played host to over 100 people from 12 different countries.

Exceeds expectations

When the Mir space station was designed and launched, it was built for a five-year life span. The Soviet Union broke down and Mir was operated by the new Russian Federal Space Agency after 1991, but it endured for almost another decade.

A series of problems, both technical and structural, caught up with Mir as years went on. Despite these failures and some accidents, it remained in operation. It was only in November 2000 that the Russian government decided to decommission the space station.

Planned re-entry

On January 24, 2001, a Russian Progress cargo ship carrying double the normal amount of fuel rendezvoused with Mir. Once the docking took place, Progress fired its thrusters to push the station into a controlled descent, thereby utilizing the extra fuel.

On March 23, 2001, Mir ceased to exist as it broke up in the Earth’s atmosphere upon re-entry. Airlines rerouted their Pacific flights and ships were warned ahead as a safety precaution. It proved to be unnecessary as the debris that did not burn up crashed into the south Pacific Ocean at the planned target zone, causing no harm to anyone.

Lucid’s tryst with Mir

On March 23, 1996, U.S. astronaut Shannon Lucid transferred to Mir from the space shuttle Atlantis for a planned five-month stay.

The first American woman to live in a space station, Lucid was also the first U.S. astronaut on an extended stay on the Mir.

As a biochemist, Lucid carried out a number of scientific experiments aboard Mir during her stay.

Her return was delayed owing to a number of reasons. She eventually made her return flight, again on Atlantis, and was back on Earth on September 26, 1996.

Her 188-day sojourn in space was a record then for time spent in space, both for women and Americans.

 

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The orbit of 2020 CD3 is unstable as it is being pulled between the gravity of the Moon and that of the Earth. So, the asteroid is expected to leave its orbit around the Earth in April. As it is on a temporary orbit around the Earth, it is considered a Temporarily Captured Object (TCO) or a temporary satellite of Earth. One it leaves its geocentric orbit around the Earth, it is expected to return to a heliocentric orbit, which is an orbit around the Sun.

What else is known about 2020 CD3?

• Astronomers have observed 2020 CD3 only about six or seven times so far.


• Its diameter is likely between 6.2 feet and 11.4 feet.


• 2020 CD3 has a chaotic orbit.


• The orbital period of 2020 CD3 around the Earth is estimated to be around 47 days


• The orbit of 2020 CD3 shows that it entered the Earth’s orbit closer to three years ago.

How did 2020 CD3 go unnoticed for years?

Asteroids like this often go undetected due to their relatively small size.

Finding such small objects is basically an accident. And there are probably many more mini-moons orbiting the Earth that we haven’t spotted yet.

The faintness of 2020 CD# and its highly-variable orbit are also cited as reasons.

When was the last time an asteroid was found orbiting the Earth?

A three-feet-wide asteroid called 2006 RH120 orbited the Earth for 18 months between 2006 and 2007. It’s expected to return in August 2028.

 

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Jupiter has 79 known moons; Saturn has 53 moons and 29 awaiting confirmation; Uranus has 27 and Neptune has 14. Even our neighbour Mars has two moons. And if you have ever felt disheartened that our our planet Earth has only one moon, while some planets have many, it is time to rejoice, albeit temporarily.

Late last month, astronomers announced that they have discovered a ‘mini-moon’, a car-sized object, orbiting the Earth. They have named it ‘2020 CD3’ for now. But this is not the type of moon that will illuminate the night sky, or be visible to the naked eye, It will not even stay there forever. Due to the instability of its path through space, the object will likely leave the Earth’s orbit sometime in April.

What exactly is this object? Let’s find out in this week’s Five Ws & One H.

Astronomers discovered a mysterious object orbiting the Earth using a 1.52-meter telescope at Mount Lemmon Observatory near Tucson, Arizona, on February 15. The Minor Planet Center, an international body that tracks asteroid discoveries, announced the find on February 25.

At first, astronomers thought the object could be a piece of junk such as a dead satellite. But as data trickled in, many realised that it was not an artificial object. It is most likely a near-Earth asteroid. (To say conclusively, astronomers would need powerful telescopes to view it.)

Asteroids are space rocks that orbit the Sun. But this asteroid orbits the Earth and that makes 2020 CD3 special. Acxcording to astronomers, it is most likely that the object was circling the Sun, when the Earth’s gravity snatched it into its orbit sometime in 2017. Since the asteroid whirls around a planet (Earth), it can be called a moon or a natural satellite. As its size is small, astronomers call it mini-moon.

Who made the discovery?

The discovery was made by Kacper Wierzchos and Theodore Pruyne, researchers for the Catalina Sky Survey (CSS). The CSS is a NASA-funded project at the University of Arizona’s Lunar and Planetary Laboratory in Tuscon, Arizona. Here researchers track near-Earth objects that could be potentially hazardous to the planet.

 

Picture Credit : Google