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By NASA
4 min read
May’s Night Sky Notes: How Do We Find Exoplanets?
Astronomers have been trying to discover evidence that worlds exist around stars other than our Sun since the 19th century. By the mid-1990s, technology finally caught up with the desire for discovery and led to the first discovery of a planet orbiting another sun-like star, Pegasi 51b. Why did it take so long to discover these distant worlds, and what techniques do astronomers use to find them?
The Transit Method
A planet passing in front of its parent star creates a drop in the star’s apparent brightness, called a transit. Exoplanet Watch participants can look for transits in data from ground-based telescopes, helping scientists refine measurements of the length of a planet’s orbit around its star. Credit: NASA’s Ames Research Center One of the most famous exoplanet detection methods is the transit method, used by Kepler and other observatories. When a planet crosses in front of its host star, the light from the star dips slightly in brightness. Scientists can confirm a planet orbits its host star by repeatedly detecting these incredibly tiny dips in brightness using sensitive instruments. If you can imagine trying to detect the dip in light from a massive searchlight when an ant crosses in front of it, at a distance of tens of miles away, you can begin to see how difficult it can be to spot a planet from light-years away! Another drawback to the transit method is that the distant solar system must be at a favorable angle to our point of view here on Earth – if the distant system’s angle is just slightly askew, there will be no transits. Even in our solar system, a transit is very rare. For example, there were two transits of Venus visible across our Sun from Earth in this century. But the next time Venus transits the Sun as seen from Earth will be in the year 2117 – more than a century from the 2012 transit, even though Venus will have completed nearly 150 orbits around the Sun by then!
The Wobble Method
As a planet orbits a star, the star wobbles. This causes a change in the appearance of the star’s spectrum called Doppler shift. Because the change in wavelength is directly related to relative speed, astronomers can use Doppler shift to calculate exactly how fast an object is moving toward or away from us. Astronomers can also track the Doppler shift of a star over time to estimate the mass of the planet orbiting it. NASA, ESA, CSA, Leah Hustak (STScI) Spotting the Doppler shift of a star’s spectra was used to find Pegasi 51b, the first planet detected around a Sun-like star. This technique is called the radial velocity or “wobble” method. Astronomers split up the visible light emitted by a star into a rainbow. These spectra, and gaps between the normally smooth bands of light, help determine the elements that make up the star. However, if there is a planet orbiting the star, it causes the star to wobble ever so slightly back and forth. This will, in turn, cause the lines within the spectra to shift ever so slightly towards the blue and red ends of the spectrum as the star wobbles slightly away and towards us. This is caused by the blue and red shifts of the star’s light. By carefully measuring the amount of shift in the star’s spectra, astronomers can determine the size of the object pulling on the host star and if the companion is indeed a planet. By tracking the variation in this periodic shift of the spectra, they can also determine the time it takes the planet to orbit its parent star.
Direct Imaging
Finally, exoplanets can be revealed by directly imaging them, such as this image of four planets found orbiting the star HR 8799! Space telescopes use instruments called coronagraphs to block the bright light from the host star and capture the dim light from planets. The Hubble Space Telescope has captured images of giant planets orbiting a few nearby systems, and the James Webb Space Telescope has only improved on these observations by uncovering more details, such as the colors and spectra of exoplanet atmospheres, temperatures, detecting potential exomoons, and even scanning atmospheres for potential biosignatures!
NASA’s James Webb Space Telescope has provided the clearest look in the infrared yet at the iconic multi-planet system HR 8799. The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI) You can find more information and activities on NASA’s Exoplanets page, such as the Eyes on Exoplanets browser-based program, The Exoplaneteers, and some of the latest exoplanet news. Lastly, you can find more resources in our News & Resources section, including a clever demo on how astronomers use the wobble method to detect planets!
The future of exoplanet discovery is only just beginning, promising rich rewards in humanity’s understanding of our place in the Universe, where we are from, and if there is life elsewhere in our cosmos.
Originally posted by Dave Prosper: July 2015
Last Updated by Kat Troche: April 2025
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By USH
Several days ago, a massive blackout swept across large parts of Spain, Portugal, and parts of southern France. Millions were left without power as the interconnected European energy grid experienced a rare and abrupt failure. While authorities quickly pointed to a "rare atmospheric phenomenon" as the cause, not everyone is convinced.
Here are some explanations of authorities as well as controversial theories:
According to REN, Portugal’s national electricity grid operator, the blackout was triggered by a fault originating in Spain’s power infrastructure. The disruption, they claim, was linked to "induced atmospheric variation", a term referring to extreme temperature differences that led to anomalous oscillations in high-voltage transmission lines. These oscillations reportedly caused synchronization failures between regional grid systems, ultimately sparking a chain reaction of failures across the European network.
What makes the situation even more intriguing is that just days before the blackout, Spain hit a historic energy milestone. On April 16, for the first time, the country’s electricity demand was met entirely by renewable energy sources - solar, wind, and hydro, during a weekday. It raises questions whether the outage was caused by a technical failure of this new renewable energy system.
While this achievement is noteworthy, it also exposes the fragility of a grid increasingly reliant on variable energy sources, especially solar, which can fluctuate dramatically with weather and atmospheric conditions.
Despite official explanations, some experts and observers remain skeptical. There were no solar flares or geomagnetic storms in the days leading up to the blackout, and solar activity had been relatively calm. Critics argue that while atmospheric disturbances may have played a role, they are not sufficient to explain such a widespread, synchronized failure.
Despite the fact that the blackout this time was probably not caused by solar flares or geomagnetic storms it has been proven that Earth’s magnetic shield is rapidly weakening, leaving us increasingly vulnerable to powerful solar storms. The magnetic north pole is accelerating toward Siberia, and the South Atlantic Anomaly continues to expand, ominous signs that a looming plasma event could bring consequences far beyond just technological disruption.
This has led to speculation that the blackout could have been intentional, possibly even a test run for handling future crises or threats to infrastructure.
Among the more controversial theories is the suggestion that this event might have involved the use of a graphite bomb, a non-lethal weapon designed to disable power grids. These devices disperse ultra-fine carbon filaments into high-voltage power lines, causing short circuits by creating conductive paths between lines. Such an attack would appear as a grid malfunction but could be devastating in scale.
Another controversial theory is that the outage has been caused by weather manipulation systems such as HAARP or the Ice Cube Neutrino observatory, constructed at the Amundsen–Scott South Pole Station in Antarctica.
Could this have been a covert drill or a demonstration of vulnerability? Some point to global forums, such as the World Government Summit, where figures like Klaus Schwab have warned about Black Swan: An unpredictable event that is beyond what is normally expected of a situation and has potentially severe consequences.
Whether the blackout was triggered by a rare natural event, a technical failure, or something more deliberate, it seems only a matter of time before we face a true Black Swan event. View the full article
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By European Space Agency
Each year, cutting-edge technologies developed by the European Space Agency (ESA) for its complex missions and scientific discoveries find new life in applications used to benefit Earth and improve our daily lives.
From 9–13 April, ESA was guest of honour at the 50th International Exhibition of Inventions Geneva in Switzerland with more than 1000 inventions, which attracted 30 000 visitors from the public. ESA showcased its new technologies and applications that have been invented for space missions and patented for use in and outside the space arena.
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By European Space Agency
The European Space Agency's XMM-Newton is playing a crucial role in investigating the longest and most energetic bursts of X-rays seen from a newly awakened black hole. Watching this strange behaviour unfold in real time offers a unique opportunity to learn more about these powerful events and the mysterious behaviour of massive black holes.
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Double Asteroid Redirection Test required extreme precision in mission planning to achieve its mission of impacting an asteroid. The founders of Continuum Space worked on astrodynamics relating to this mission, which they used to inform their product.NASA Planning space missions is a very involved process, ensuring orbits are lined up and spacecraft have enough fuel is imperative to the long-term survival of orbital assets. Continuum Space Systems Inc. of Pasadena, California, produces a cloud-based platform that gives mission planners everything they need to certify that their space resources can accomplish their goals.
Continuum’s story begins at NASA’s Jet Propulsion Laboratory in Southern California. Loic Chappaz, the company’s co-founder, started at JPL as an intern working on astrodynamics related to NASA’s Double Asteroid Redirection Test. There he met Leon Alkalai, a JPL technical fellow who spent his 30-year career at the center planning deep space missions. After Alkalai retired from NASA, he founded Mandala Space Ventures, a startup that explored several avenues of commercial space development. Chappaz soon became Mandala’s first employee, but to plan their future, Mandala’s leadership began thinking about the act of planning itself.
Because the staff had decades of combined experience at JPL, they knew the center had the building blocks for the software they needed. After licensing several pieces of software from JPL, the company began building planning systems that were highly adaptable to any space mission they could come up with. Mandala eventually evolved into a venture firm that incubated space-related startups. However, because Mandala had invested considerably in developing mission-planning tools, further development could be performed by a new company, and Continuum was fully spun off from Mandala in 2021.
Continuum’s platform includes several features for mission planners, such as plotting orbital maneuvers and risk management evaluations. Some of these are built upon software licensed from the Jet Propulsion Laboratory.Continuum Space Systems Inc. Continuum’s tools are designed to take a space mission from concept to completion. There are three different components to their “mission in a box” — design, build and test, and mission operations. The base of these tools are several pieces of software developed at NASA. As of 2024, several space startups have begun planning missions with Continuum’s NASA-inspired software, as well as established operators of satellite constellations. From Continuum to several startups, NASA technologies continue to prove a valuable foundation for the nation’s space economy.
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