As they are very small, very dim, and very far away, seeing them directly is extremely challenging and rare. As such, we usually infer their presence from their effects on their host stars – which means that when we do, on the odd occasion, see one directly, it’s a cause for excitement.
And excitement is exactly what you should be feeling with the discovery of an exoplanet called COCONUTS-2b, orbiting a star called COCONUTS-2.
Not only is COCONUTS-2b (named for the COol Companions ON Ultrawide orbiTS survey) the closest directly imaged exoplanet to Earth to date – at a distance of just 35 light-years – it’s a rarity among exoplanet discoveries: a relatively cool, massive gas giant, orbiting its star at a great distance.
“With a massive planet on a super-wide-separation orbit, and with a very cool central star, COCONUTS-2 represents a very different planetary system than our own Solar System,” said astronomer Zhoujian Zhang of the University of Hawaiʻi Institute for Astronomy.
COCONUTS-2b, red dot at top-left. (Zhang et al., The Astrophysical Journal Letters, 2021)
The most common methods for detecting an exoplanet rely on two effects exoplanets might have on a host star. The first is called the transit method, and it relies on changes in the depth of a star’s light. When an exoplanet passes between us and its host star on its orbital path, this transit is detectable as faint dips in the star’s light.
The radial velocity (or ‘wobble’) method, relies on changes in the wavelength of a star’s light. As the exoplanet orbits the star, it exerts a slight gravitational influence that causes the star to wobble minutely. As it moves in a small circular motion, the wavelength of its light shifts slightly as it moves towards and away from us.
Both these methods are best able to detect exoplanets that are massive, and close to the planet – massive, because the signal will be larger and easier to discern, and close because they orbit quickly, which means astronomers can obtain the multiple signals they need in order to confirm that they are caused by an orbiting body and not a random passing object.
It was, however, the large distance from its host star – around 6,471 astronomical units, which is 6,471 times the average distance between Earth and the Sun – that made COCONUTS-2b visible in direct images. At that distance, its orbital period is approximately 1.1 million years (which might be a record for a known exoplanet).
“Directly detecting and studying the light from gas-giant planets around other stars is ordinarily very difficult, since the planets we find usually have small-separation orbits and thus are buried in the glare of their host star’s light,” said astronomer Michael Liu of the University of Hawai’i.
What made it visible is that, although it’s cool for a gas giant exoplanet, it’s still pretty warm, with a temperature of around 434 Kelvin (161 degrees Celsius, or 322 degrees Fahrenheit), in spite of its distance from the warmth of the star.
COCONUTS-2b is still quite young, up to only around 800 million years; its warm temperature is residual heat from the exoplanet’s formation, trapped inside the massive exoplanet, six times the mass of Jupiter. This heat means that the exoplanet faintly glows in infrared wavelengths – enough to be discernible in direct images.
Its huge orbital distance will have other benefits for future research, too. It may be able to help us better understand how gas giants form, a process that we still don’t understand very well – and taking a closer look at it will help us better understand gas giant diversity.
“With its huge orbital separation, COCONUTS-2b will be a great laboratory for studying the atmosphere and composition of a young gas-giant planet,” Liu said.
The research has been published in The Astrophysical Journal Letters.
Less than three days after SpaceX completed its 20th successful Falcon 9 launch of 2021, a small Long March 2D rocket carried the country of China past the same 20-flight milestone.
Excluding SpaceX and China, the rest of the world combined completed its 20th orbital launch hours before SpaceX when US startup Virgin Orbit’s LauncherOne rocket successfully flew for the second time. In simpler terms, relative to any other country, space agency, or company, SpaceX has led the world in orbital launches for the first half of 2021 – the first time in history a single company has managed that feat.
Perhaps more importantly, as CEO Elon Musk has frequently noted over the last several months, total mass launched to orbit is an even more valuable measure of success and in that regard, SpaceX leads the rest of the world combined. In the first half of 2021, SpaceX has successfully launched more than 230 metric tons (~500,000 lb) of spacecraft, Dragons, space station cargo, and astronauts to orbit and grown its Starlink internet constellation by almost 800 satellites.
Falcon 9 is almost always at max capacity. When it has “spare” performance, it flies back to land, which costs much less than using a droneship.
Our fundamental constraint is mass to orbit per unit time. Last year, SpaceX launched roughly double payload mass of rest of world.
— Elon Musk (@elonmusk) March 11, 2021
As of July 3rd, the rest of the world combined – including China, Russia, India, and three other US providers – have launched approximately 175 tons (385,000 lb) to orbit in 2021. According to Musk, SpaceX effectively doubled the rest of the world’s payload mass to orbit in 2020, meaning that other launch providers – mostly led by China – are significantly more competitive in 2021, though they’ve still launched ~25% less mass than SpaceX.
As far as specific launch vehicles go, SpaceX also retains an almost unbeatable lead with Falcon 9. Only Russia comes vaguely close with 11 successful Soyuz 2.1 launches so far, followed by China’s Long March 4 with 7 flights this year.
Nevertheless, on July 1st, a Russian Soyuz 2.1 rocket launched OneWeb’s eighth batch of low Earth orbit (LEO) internet satellites, pushing the rest of the non-China/SpaceX world to 21 successful launches in 2021. China’s July 3rd launch was its 20th successful orbital mission but the country is set to launch again – this time carrying a weather satellite – as early as July 4th. Given China’s ambitious manifest, it’s possible that SpaceX won’t catch up before the end of 2021, but the lone company and its reusable Falcon 9 workhorse rocket are still on pace to launch 40 times (or more) this year alone.
SpaceX’s Falcon 9 rocket is dominating global orbital launches in 2021
Typically when SpaceX sends a Crew Dragon spacecraft into orbit, it’s headed to the ISS to deliver astronauts and cargo. Recently, SpaceX announced that it would be launching the world’s first all-civilian crew into orbit and was targeting a launch date as early as September. Some new details about the spacecraft and how the civilian crew will live while aboard have surfaced, and it’s very interesting.
It turns out the crew aboard the Dragon capsule will have the best view from the bathroom you could ask for. An incredible view from the toilet is enabled because SpaceX replaced the normal docking connector in the capsule’s nose with a cupola. The toilet happens to be in that cupola, and a curtain separates the person needing to do their business from the rest of the crew.
That means while the civilian astronauts are using the facilities, they will be able to stare out at the earth and into deep space. It’s described as the first space toilet with a 360-degree view. According to mission commander Jared Isaacman, passengers will be able to look out the window as they handle their business. Isaacman is a billionaire entrepreneur and pilot who purchased four seats on the SpaceX capsule for the first civilian mission to space.
The mission is the first ever to have no professional astronauts on board. Issacman said there isn’t a ton of privacy, and apparently, the toilet wasn’t purposefully designed to have an incredible view. It just happens to be positioned where the cupola is. The mission has been dubbed Inspiration4 and could launch as early as September 15.
The crew is expected to orbit the earth at an altitude higher than the ISS for three days and conduct experiments while in orbit. The real purpose of the cupola is to allow the passengers to view Earth and look into space. The toilet just happens to be positioned in that area.
Gen. David Thompson: “The more we can depend on commercial space for routine activities like transportation and debris removal, the more we can focus on national security.”
WASHINGTON — Vice Chief of Space Operations of the U.S. Space Force Gen. David Thompson said it would make sense for the government to pay companies to clean up space junk if such services existed.
Orbital debris represents a risk to spacecraft and to safe operations in space, Thompson said March 16 in an interview with national security analyst John Nagl, of the Foreign Policy Research Institute.
“I’ll pay by the ton if they can remove debris,” Thompson said, noting that there are no companies that can do that today.
Nagl said someone in the audience asked if Thompson has heard of Astroscale, a Japan-based company with operations in Denver, Colorado, that plans to launch a debris-removal mission later this week.
Thompson said he was not aware of the company. “I’m going to have to go Google that,” he said.
Regardless of which companies in the space industry end up successfully providing space junk cleaning services, the Space Force would be a customer, Thompson said.
“The more we can depend on commercial space for routine activities like transportation and debris removal, the more we can focus on national security,” he said.
Space debris includes human-made objects like nonfunctional spacecraft and abandoned launch vehicle stages, and fragments from the breakup of rocket bodies and spacecraft.
The European Space Agency estimates there are 3,600 working satellites in orbit and 28,200 debris objects. More than 10,000 satellites are scheduled to launch to low Earth orbit over the next decade.
Astroscale on Saturday will fly the first commercial mission to demonstrate space debris docking and removal technologies. The company will launch a satellite called End-of-Life Services by Astroscale demonstration (ELSA-d) on a Russian Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan.
The ELSA-d spacecraft has a a servicer and a client satellite that will be launched together. The servicer will use proximity rendezvous technologies to dock with the client satellite that will simulate a piece of debris.
China has released epic video footage from the country’s Tianwen-1 spacecraft as it made a close approach to Mars after reaching the Red Planet this week.
Tianwen-1 arrived at Mars on Wednesday (Feb. 10) and fired its engines to allow it to enter orbit around the planet. China has now received and put together a series of images taken during this approach and created two remarkable scenes, seen here in a single video.
One video, taken by Tianwen-1’s small engineering survey sub-system camera for monitoring a solar array, shows Mars entering into frame followed by an incredible view of the edge of Mars’ atmosphere, or “atmospheric limb.”
Video: Watch China’s Tianwen-1 arrive at Mars See more: China’s Tianwen-1 Mars mission in photos
China’s Tianwen-1 Mars orbiter captured this view of the Red Planet as it entered orbit around the planet on Feb. 10, 2021. (Image credit: CCTV/CNSA)
Craters are also visible on the planet’s surface, while the solar panel appears to oscillate with the spacecraft firing its main engines to decelerate.
A second video is from the point of view of a monitoring camera for Tianwen-1’s tracking antenna, providing similarly amazing footage.
The engineering survey sub-system consists of a number of small monitoring cameras used to monitor processes such as the deployment of solar arrays and other events, according to the China National Space Administration.
The cameras took photos once every three seconds and continuously photographed for around half an hour. The videos have a frame rate of about 10 pictures per second.
Related: Here’s what China’s Tianwen-1 Mars mission will do
Another Mars view from China’s Tianwen-1 orbiter taken as it entered orbit around the planet on Feb. 10, 2021. (Image credit: CCTV/CNSA)
Tianwen-1, which means “Questioning the Heavens,” launched on July 23, 2020 and is China’s first independent interplanetary mission. It arrived in orbit around Mars after a 202-day, 295-million-mile (475 million kilometers) journey through deep space. It snapped an image of the Red Planet during its final approach.
The spacecraft consists of both an orbiter and a rover. The landing attempt for the rover is not expected until May or June, giving the orbiter time to image and map out the intended landing site in a region known as Utopia Planitia.
Tianwen-1’s roughly 530-lb. (240 kilograms) solar-powered rover carries science payloads to investigate surface soil characteristics and search for potential water-ice distribution with a ground penetrating radar. The rover also carries a panoramic camera similar to one aboard China’s Yutu 2 rover, which is currently exploring the the far side of Earth’s moon.
The Tianwen-1 orbiter will study the Red Planet’s surface with medium- and high-resolution cameras and a sounding radar, and make other detections with a magnetometer and particle detectors.
200 light-years away from Earth, there’s a K-type main-sequence star named TOI (TESS Object of Interest) 178. When Adrian Leleu, an astrophysicist at the Center for Space and Habitability of the University of Bern, observed it, it appeared to have two planets orbiting it at roughly the same distance. But that turned out to be incorrect. In fact, six exoplanets orbit the smallish star.
And five of those six are locked into an unexpected orbital configuration.
Five of the planets are engaged in a rare rhythmic, dance around the star. In astronomical terms, they’re in an unusual orbital resonance, which means their orbits around their star display repeated patterns. That property makes them an intriguing object of study and one that could tell us a lot about how planets form and evolve.
“Through further observations, we realized that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration.”
Adrian Leleu, Center for Space and Habitability, University of Bern.
Adrian Leleu leads a team of researchers who studied the unusual phenomenon. They presented their findings in a paper titled “Six transiting planets and a chain of Laplace resonances in TOI-178.” The paper is published in the journal Astronomy and Astrophysics.
In the team’s initial observations, it appeared there were only two planets, as five of them move in such a way as to deceive the eye. But further observations showed that something else was happening in the system. “Through further observations, we realized that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration,” said lead author Leleu.
In this artist’s animation, the rhythmic movement of the planets around the central star is represented through a musical harmony, created by attributing a note (in the pentatonic scale) to each of the planets in the resonance chain. This note plays when a planet completes either one full orbit or one half orbit; when planets align at these points in their orbits, they ring in resonance. Credit: ESO
TOI-178’s orbital resonance is similar to another familiar orbital resonance right here in our own Solar System. That one encompasses Jupiter’s moons Io, Europa, and Ganymede.
The orbital resonance shared by Ganymede, Europa, and Io is fairly simple. Io makes four full orbits for every single orbit of Ganymede and two full orbits for Europa’s full orbit. But the planets around TOI-178 have a much more complex relationship.
TOI-178’s five outer planets are in a 18:9:6:4:3 chain of resonance. The first in the chain and second from the star completes 18 orbits, the second in the chain and third from the star completes 9 orbits, and it continues on from there. The closest planet to the star isn’t part of the chain.
For a system to be orbiting its star in such an orderly and predictable fashion, conditions had to be relatively sedate in this system. Giant impacts or planet migrations would have disrupted it. “The orbits in this system are very well ordered, which tells us that this system has evolved quite gently since its birth,” explained co-author Yann Alibert from the University of Bern.
But there’s more.
In our Solar System the small inner planets are all rocky, while the planets in the outer Solar System are large and gaseous. Beyond Neptune is a region of ice dwarf planets and Kuiper Belt Objects. Image credit: NASA/JPL/IAU
In our Solar System, the inner planets are rocky, and the planets beyond the asteroid belt are not; they’re gaseous. This is one of those instances where we might be tempted to think our Solar System represents some sort of norm. But the TOI-178 system is much different. Gaseous and rocky planets are not delineated like in our system.
“It appears there is a planet as dense as the Earth right next to a very fluffy planet with half the density of Neptune, followed by a planet with the density of Neptune. It is not what we are used to,” said Nathan Hara from the Université de Genève, Switzerland, one of the researchers involved in the study.
“This contrast between the rhythmic harmony of the orbital motion and the disorderly densities certainly challenges our understanding of the formation and evolution of planetary systems,” says Leleu.
The team used some of the European Observatory’s most advanced, flagship instruments in this work. The ESPRESSO instrument on the VLT, and the NGTS and SPECULOOS instruments at the ESO’s Paranal Observatory. They also used the European Space Agency’s CHEOPS exoplanet satellite. These instruments all specialize in one way or another with the study of exoplanets, which are virtually impossible to detect with a “regular” telescope.
Exoplanets are a long way away from Earth, and the overpowering light from their stars makes them nearly invisible in a regular optical telescope.
The instruments used in this study detect and characterize exoplanets in a couple of different ways. But it all comes down to detecting light. The transiting method used by the NGTS (Next-Generation Transit Survey), CHEOPS (Characterizing ExOPlanet Satellite), and SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) detect the dip in starlight when an exoplanet passes in front of its star. The radial velocity method employed by ESPRESSO detects shifts in the starlight’s normal spectrum when an exoplanet tugs on the star and shifts its position ever so slightly.
By using multiple instruments with different methods and capabilities, the team was able to characterize the system in detail. The innermost planet in the system, which is not in resonance with the others, moves the fastest. It completes an orbit in just two Earth days. The slowest planet moves ten times slower than that. The planet sizes range from one to three Earth sizes, and the masses range from 1.5 to thirty times Earth’s mass.
The orbital resonance of the planets is in an exquisite balance. The authors write that “The orbital configuration of TOI-178 is too fragile to survive giant impacts, or even significant close encounters… a sudden change in period of one of the planets of less than a few .01 d can render the system chaotic.” They also write that their data “…shows that modifying a single period axis can break the resonant structure of the entire chain.”
This discovery just means more work for astronomers. The unusual orbital resonance and positions of the planets means they need to rethink some of our theories around the formation and evolution of planets and solar systems.
This figure from the study compares the density, mass, and equilibrium temperature of the TOI-178 planets with other exoplanet systems. In Kepler-60, Kepler-80, and Kepler-223, the density of the planets decreases when the equilibrium temperature decreases. Contrary to the three Kepler systems, in the TOI-178 system, the density of the planets is not a growing function of the equilibrium temperature. The team behind this study says that if they can understand why the TOI-178 system is different, it could become a sort of Rosetta Stone for deciphering solar system and planetary development. Image Credit: Leleu et al, 2021.
As the authors write in their paper: “Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present.”
The nebular hypothesis, also called the Solar Nebular Disk Model (SNDM), is the working theory for the formation of our Solar System and others. According to the model, a giant molecular cloud undergoes gravitational collapse, and when enough gas gathers together, it eventually begins fusion, and a star’s life begins. Most of the material in the cloud will be taken up by the star, and in our Solar System, the Sun has the lion’s share: about 99.86%.
The remaining material makes up the protoplanetary disk, which rotates around the star in a flattened pancake shape. As material clumps together in the rotating protoplanetary disk, it eventually forms planets. There are some problems with the nebular hypothesis, and other theories have tried to explain them.
These are images of nearby protoplanetary disks. At the center of each one is a young star, and the gaps are in the disks are caused by forming exoplanets. Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello
But this system challenges that theory. The SNDM suggests that rocky, terrestrial planets form nearer the star. They start out as planetary embryos and through violent mergers create planets like Venus, Mercury, Mars, and Earth. Gas giants, according to the SNDM, form out beyond the Solar System’s frost line, where planet embryos form out of frozen volatiles.
But the TOI-178 system challenges that understanding. If the planets in that system followed the SNDM, then the gas planets would be further from the star, and the rocky planets would be closer. Since they’re not, something must have disrupted them. But if something disrupted them, their orbits wouldn’t be choreographed in such an exquisite rhythm. It’s a conundrum.
“Understanding, in a single framework, the apparent disorder in terms of planetary density on one side and the high level of order seen in the orbital architecture on the other side will be a challenge for planetary system formation models,” they write.
Systems like this are challenging to understand, but ultimately, they drive researchers to think harder and to observe more fully.
As the team of scientists write in their conclusion: “The TOI-178 system, as revealed by the recent observations described in this paper, contains a number of very important features: Laplace resonances, variation in densities from planet to planet, and a stellar brightness that allows a number of followup observations (photometric, atmospheric, and spectroscopic). It is therefore likely to become one of the Rosetta Stones for understanding planet formation and evolution, even more so if additional planets continuing the chain of Laplace resonances is discovered orbiting inside the habitable zone.”
