We're here to help you navigate STEM learning at home while schools are closed due to COVID-19.

Here are some resources to guide your at home learning:

Exoplanets

Introduction

An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmation of an exoplanet detection occurred in 1992. As of 1 October 2019, there are 4,118 confirmed exoplanets in 3,063 systems, with 669 systems having more than one planet.

Drawing with 4 smallest planets of Kepler-90 larger than smallest planets in solar system, 4 largest planets similar size.
Figure 1. Artist's conception of exoplanets in Kepler-90 system compared to solar system.

Poster showing fictional party goers on exoplanet.
Figure 2. A NASA travel poster "spoof." Discovered in October 2013 using direct imaging, PSO J318.5-22 belongs to a special class of planets called rogue, or free-floating, planets. Wandering alone in the galaxy, they do not orbit a parent star. Not much is known about how these planets come to exist, but scientists theorize that they may be either failed stars or planets ejected from very young systems after an encounter with another planet. These rogue planets glow faintly from the heat of their formation. Once they cool down, they will be dancing in the dark.

 

There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected as of 2019 are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like stars have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.

There are planets that are so near to their star that they take only a few hours to orbit and there are others so far away that they take thousands of years to orbit. Some are so far out that it is difficult to tell whether they are gravitationally bound to the star. Almost all of the planets detected so far are within the Milky Way. Nonetheless, evidence suggests that extragalactic planets, exoplanets farther away in galaxies beyond the local Milky Way galaxy, may exist. The nearest exoplanet is Proxima Centauri b, located 4.2 light-years (1.3 parsecs) from Earth and orbiting Proxima Centauri, the closest star to the Sun.

The discovery of exoplanets has intensified interest in the search for extraterrestrial life. There is special interest in planets that orbit in a star's habitable zone, where it is possible for liquid water, a prerequisite for life on Earth, to exist on the surface. The study of planetary habitability also considers a wide range of other factors in determining the suitability of a planet for hosting life.

Besides exoplanets, there are also rogue planets, which do not orbit any star. These tend to be considered as a separate category, especially if they are gas giants, in which case they are often counted as sub-brown dwarfs, like WISE 0855−0714. The rogue planets in the Milky Way possibly number in the billions (or more). [Source: Wikipedia https://en.wikipedia.org/wiki/Exoplanet]

Poster showing fictional tourists on an exoplanet looking out of a vehicle window at a city.
Figure 3. Another NASA travel poster "spoof." Some 40 light-years from Earth, a planet called TRAPPIST-1e offers a heart-stopping view: brilliant objects in a red sky, looming like larger and smaller versions of our own moon. But these are no moons. They are other Earth-sized planets in a spectacular planetary system outside our own. These seven rocky worlds huddle around their small, dim, red star, like a family around a campfire. Any of them could harbor liquid water, but the planet shown here, fourth from the TRAPPIST-1 star, is in the habitable zone, the area around the star where liquid water is most likely to be detected. This system was revealed by the TRAnsiting Planets and PlanetIsmals Small Telescope (TRAPPIST) and NASA's Spitzer Space Telescope.

Resources

Resource Type
Trusted Partner Content
News Article EurekAlert!
June 13, 2018
Two independent teams of astronomers have used ALMA to uncover convincing evidence that three young planets are in orbit around the infant star HD 163296. Using a novel planet-finding technique, the astronomers identified three disturbances in the gas-filled disc around the young star: the strongest evidence yet that newly formed planets are in orbit there. These are considered the first planets to be discovered with ALMA. Read more
Trusted Partner Content
News Article EurekAlert!
February 28, 2019
Paul Kalas of UC Berkeley was puzzled by the tilted but stable orbit of a planet around a binary star -- an orbit like that of our solar system's proposed Planet Nine. He calculated backwards in time to see if any of the 461 nearby stars ever came close enough to perturb the system. One star fit the bill. The stellar flyby 2-3 million years ago likely stabilized the planet's orbit, keeping it from flying away. Read more
Trusted Partner Content
News Article Scientific American
August 5, 2019
Astronomers could soon learn whether or not the nearest neighboring star system harbors habitable worlds Read more
Trusted Partner Content
News Article EurekAlert!
September 4, 2018
Astronomers from the Department of Physics at the University of Tokyo discovered a dense disk of material around a young star, which may be a precursor to a planetary system. Their research could vastly improve models of how solar systems form, which would tell us more about our own place in the cosmos. Read more
Trusted Partner Content
News Article EurekAlert!
March 13, 2019
Researchers at the University of Sydney have mapped out how carbonate formations formed from 'marine snow' have helped regulate Earth's temperature over 120 million years. Dr Andria Dutkiewicz warns that global warming could release some of that carbon into the atmosphere. Read more
Trusted Partner Content
News Article Science News
March 11, 2020
Astronomers saw hints of iron rain on an ultrahot gas giant, an exoplanet where starlike atmospheric temperatures drive weird weather. Read more
Trusted Partner Content
News Article Scientific American
September 19, 2018
A new study suggests a strange and surprisingly lively geological cycle for the small world Read more
Trusted Partner Content
News Article EurekAlert!
November 19, 2019
Iowa State astronomers are part of an international team that has been analyzing data from NASA's TESS Mission. The astronomers describe their study of two red-giant stars -- older, 'retired' stars no longer burning hydrogen in their cores -- in a paper recently published by The Astrophysical Journal. The study details an interesting case of planetary evolution and demonstrates how star studies can be an important part of the mission's search for planets beyond our solar system. Read more
Trusted Partner Content
News Article EurekAlert!
January 15, 2020
An analysis of cyclical changes in the light spectrum emitted by Proxima Centauri, the star closest to the Sun, suggests it may be orbited by a second planet. Mario Damasso and colleagues present data suggesting that this candidate planet orbits Proxima Centauri every 5.2 years and may be a 'super-Earth,' with a mass higher than Earth's, though much lower than that. Read more
Trusted Partner Content
News Article EurekAlert!
December 14, 2018
Astronomers have captured one of the most detailed views of a young star taken to date, and revealed an unexpected companion in orbit around it. Read more
< 1 ... 5 6 7 8 9 ... 175 >

Other Resources

Free science fair projects.