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Edward Guinan, PhD - Villanova University. Villanova, PA, US

Edward Guinan, PhD

Professor of Astrophysics and Planetary Sciences | College of Liberal Arts and Sciences | Villanova University


Edward Guinan, PhD, an expert in astronomy and space science research explores the sun, stars, planets, extraterrestrial life potential.






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Growing Food on Mars



Areas of Expertise (6)

Stellar Astrophysics Including Solar Activity and Flares


Exoplanets and the Suitability of Exoplanets for Life

Pulsating Stars and Stellar Evolution

Interstellar Travel Potential

Severe & Hazardous Weather / Global Warming


Dr. Guinan is a pioneer in astronomy and space science research that studies our Sun, stars, and planets inside and outside our solar system as well as the search for potential life on these planets. His recent research efforts are primarily aimed at studying the effects that X-ray and UV from host stars have on their planets and to determine if these exoplanets could be habitable. Dr. Guinan also carries out research in astrobiology on Earth to study extremophiles (life in extreme conditions) as proxies for potential life on Venus, Mars, and Titan. A principal and guest investigator on numerous NASA astronomy and NASA and NSF sponsored research programs, Dr. Guinan is adept at presenting complex astronomical concepts in a lively, clear fashion.

Dr. Guinan is active in establishing and promoting astronomy education worldwide. He is a founding member of the African Astronomical Society (AfAS) and the East Africa Astronomical Society (EAAS). Dr. Guinan also served as the Chair of the International Astronomy Union’s (IAU) Teaching Astronomy for Development (TAD) program and was Co-chair of the International School of Young Astronomers (ISYA) for over 10 years. In these programs he helped organize schools and workshops in dozens of developing countries. Currently he is the Co-chair of the IAU Office for Astronomy Development (OAD) Task Force that stimulates and supports astronomy research and education at universities in many developing countries. In addition, since 2012 he helps organize and participated in several CARIB-STEM programs held at the University College of the Cayman Islands (UCCI).

In addition to this international outreach work, Dr. Guinan has served on the Council of the American Astronomical Society (AAS). He currently is serving on the AAS Publication Board. While a member of the AAS council he and two colleagues initiated a travel grant program to support the attendance of minorities at meetings of the American Astronomical Society: Funds for Astronomical Meetings: Funds for Astronomical Meetings: Outreach to Underrepresented Scientists (FAMOUS).

Education (2)

University of Pennsylvania: PhD

Villanova University: BS

Select Accomplishments (6)

Alcott Medal for Distinguished Service from the American Association of Variable Star Observers (professional)


Outstanding Mentoring & Teaching Award Villanova University (professional)


One of first to observe rings around Neptune (professional)

1982 Guinan and Villanova colleague Frank Maloney found evidence of rings around the planet Neptune. Their discovery was confirmed in 1989 by NASA’s Voyager Mission.

Helped establish the Biruni Observatory in Shiraz, Iran. (professional)


Kepler Mission Guest Investigator (professional)

2010-2015 Keppler Mission searched for and discovered Earth-size exoplanets.

International Astronomical Union's Global Astronomy, Education and Outreach (professional)

Active in establishing and promoting international astronomy education, research and outreach programs in developing countries. These include the International School for Young Astronomers (ISYA) and Teaching Astronomy for Development (TAD). Since 2012 he has been the Chair of the Astronomy for Universities and Research Program at the IAU Office of Astronomy for Development (IAU/OAD). In addition, he participates in CARIB-STEM programs held at the University College of the Cayman Islands (UCCI).

Affiliations (4)

  • IAU Office for Astronomy Development (OAD): Task Force for Education and Research in Universities
  • International Astronomical Union
  • American Astronomical Society
  • American Association of Variable Star Observers (AAVSO)

Select Media Appearances (18)

New Calculations Have Raised Concerns Popular Eclipse Maps Might Be Off. Here’s What Scientists Say

CNN  online


And for viewing purposes, NASA scientists and other experts recommend that spectators head for the middle, rather than the perimeter, of the path anyway. “I would never, never be near the edge of where that totality is because it’s a difference between night and day,” said Dr. Edward Guinan, a professor of astronomy and astrophysics at Villanova University.

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An Unusual Green Comet Has Eagles Fans Excited Ahead of the NFC Championship Game

Philadelphia Inquirer  online


For the scientific details on the comet, including why it appears green, we spoke to Bochanski and Ed Guinan, a Villanova professor of astronomy and astrophysics.

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Is there a planet out there even better than Earth?

Big Think  online


Earth has a vast biosphere, with a huge amount of biomass, mostly in the form of photosynthesizing organisms. It also has a lot of biodiversity. So, if we are to look for a world more habitable than Earth, we need to find a place with even more biomass and biodiversity. Such planets — still theoretical — are sometimes referred to as “superhabitable.” But are they real? René Heller from the Max-Planck Institute in Göttingen, Ed Guinan from Villanova University, and I have argued that the answer is yes. And we propose a number of ways they could come to exist.

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The dimming of Betelgeuse: ‘We have directly witnessed the formation of so-called stardust’

The Independent  online


Betelgeuse, to put it most politely, burped. In the autumn of 2019 the star, a red supergiant at the shoulder of the constellation Orion the Hunter, began to dim drastically to less than half its usual brightness, and some astronomers worried — or perhaps were hoping — that it would explode in a supernova. Astronomers now say that dust was the culprit in the Great Dimming and that Betelgeuse itself was responsible for that dust. A giant blob of gas erupted from the star, the story goes, and then cooled off and condensed into solid particles that temporarily veiled their origin. ... But Edward Guinan, of Villanova University, who has followed Betelgeuse intently, was more measured in this enthusiasm. Three other studies favour the growth of cool regions on the surface of the star to explain the significant decrease in light.

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Our Apollo-inspired dreams of living on the moon could still come true

CNET  online


n 1968, Edward Guinan was a young graduate student studying the universe from an observatory in New Zealand. And like countless members of the Apollo generation, he anticipated the moon landing by Neil Armstrong and Buzz Aldrin the following year would be the start of Manifest Destiny, lunar edition. He believed landing on the moon was just the beginning. "I was a space advocate, I was involved with building rockets and things of that sort, so I was a big fan of the program," Guinan, who would go on to have a pioneering career in astrophysics and planetary science at Villanova University, tells me.

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Primitive life is possible on nearby exoplanet, scientists say

CNN (picked up by more than 75 outlets  online


Astronomers believe that recently discovered super-Earth Barnard's star b, only six light-years away, might be able to support life. … The planet is probably dimly lit by its star and slightly colder than Saturn. The researchers believe that it is an icy desert with no liquid water, a hostile environment where the average surface temperature is around minus-274 degrees Fahrenheit. But Villanova University astrophysicists Edward Guinan and Scott Engle announced Thursday that they believe life could function in an unusual way on the frozen planet. The announcement was made during the 233rd meeting of the American Astronomical Society in Seattle.

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Villanova astronomer among team discovering Super Earth

KYW News Radio (Philadelphia)  radio


A Villanova astronomy and planetary science professor is among an international team of astrophysicists who have discovered a planet known among scientists as a Super Earth. Professor Edward Guinan said the discovery of the planet was made near what is called Barnard's Star.

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5 Questions That Make Astrobiologists Squirm

Forbes  online


Based on research done with Villanova University astronomer Edward Guinan, Cuntz still thinks advanced life forms have the highest likelihood to exist in the environments of certain orange dwarf stars that are still in their main sequence hydrogen-burning phases.

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Researchers report long hidden properties of Polaris

phys.org.com  online


Two Villanova University astrophysics professors led a research team that has discovered the long hidden physical properties of Polaris, popularly known as "The North Star." Until now, scientists' wide-ranging estimates of the star's distance from the Earth (322-520 light years), made determining its physical makeup difficult. But, equipped with precise distance measurements recently made by the European Space Agency's (ESA) Gaia Mission (447+/- 1.6 light years), the Villanova team has been able to determine Polaris's radius, intrinsic brightness, age and mass.

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Edward Guinan, Villanova University – Growing Food on Mars

The Academic Minute, WAMC Radio  radio


Could we grow food on Mars? Edward Guinan, professor of astronomy at Villanova University, answers this question.

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Mars bar won’t have beer, but dandelion wine is a possibility

WHYY 90.9 FM (Philadelphia NPR Affiliate)  radio


After breaking ground as one of the first college courses on studying how to grow food on Mars, an astrobiology class at Villanova University is gearing up for another semester’s harvest as students continue experimenting in theoretic agriculture. When choosing a plants for Mars, you want something that’s renewable, doesn’t need a lot of light, and is very hardy, said astronomer and professor Edward Guinan. That includes some greenery that could figure in alcoholic beverages.

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If We Ever Get to Mars, the Beer Might Not Be Bad

The New York Times  online


Here’s an interplanetary botany discovery that took college students and not NASA scientists to find: Hops — the flowers used to add a pleasant bitterness to beer — grow well in Martian soil. “I don’t know if it’s a practical plant, but it’s doing fairly well,” said Edward F. Guinan, a professor of astronomy and astrophysics at Villanova University. Last semester, 25 students took Dr. Guinan’s class on astrobiology, about the possibility of life elsewhere in the universe. For the laboratory part of the course, the students became farmers, experimenting to see which crops might grow in Martian soil and feed future travelers there.

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Why Harvey's assault on Texas couldn't happen here

The Philadelphia Inquirer  online


Harvey-related rains could spoil part of the holiday weekend here, but experts assure that what has occurred on the Gulf Coast simply couldn’t happen in this area. Harvey encountered ideal rain-making conditions, with gulf waters flirting with 85 degrees, noted Edward Guinan, astrophysics professor at Villanova University. This is the peak period for gulf surface temperatures in a subtropical region that essentially becomes tropical in summer, he added.

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Millions in U.S. Look Skyward During Solar Eclipse

The Wall Street Journal  online


Eyes skyward, millions of Americans were transfixed by the spectacle of a total solar eclipse midday Monday, as the moon’s shadow raced from coast to coast like a brush stroke across the canvas of the continent.

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What scientists hope to learn from the eclipse

cnn.com  online


The Eclipse of the Century may also turn into the Science Experiments of the Century. For years, scientists have been planning the studies, experiments and observations that will finally be underway on Monday. They've had to travel to their chosen spots within the path of totality and test new instruments so everything is ready for the big day. Technology has come a long way from where it was during previous eclipses visible in the US, such as the 1979 event. "Since 1979, an armada of solar telescopes (have been) deployed in orbit around the Earth and Sun to continuously monitor the Sun," Ed Guinan, a professor of astronomy and astrophysics at Villanova University, wrote in an email. "These solar missions -- more than (a) dozen of them -- keep a continuous watch on the Sun and solar activity, such a solar flares and coronal mass ejections." Guinan will be in Grand Island, Nebraska, to fly cameras on drones and make high-speed videos of the shadow bands as the eclipse shadow moves rapidly along the ground.

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Did Scientists Just Spot the First Exomoon?

Gizmodo  online


Thanks largely to NASA’s Kepler space telescope, astronomers have found thousands of exoplanets lurking outside our solar system. Finding what creeps around those planets, however, has proven itself to be incredibly challenging. While scientists have had a few close calls with exomoons over the years, so far, no discovery’s been legit. But a group of astronomers at Columbia University now think they’ve found an exomoon for real, roughly 4,000 lightyears away. “Exomoons are hard to detect because moons are typically much smaller than their host planets and thus typically don’t affect the transit eclipse light changes, except if the moon is large as in the case of this system,” Edward Guinan, a professor of astronomy and astrophysics at Villanova University, told Gizmodo. Indeed, a Neptune-sized moon would challenge our solar system-centric understanding of what a “moon” is.

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Why NASA is expanding its 'Veggie' space program

The Christian Science Monitor  online


Like any good parental figure, NASA is making sure its astronauts are eating their vegetables. On Tuesday, an Atlas V rocket blasted into space from the Cape Canaveral Air Force Station, carrying a payload of supplies and scientific equipment to the International Space Station (ISS). Onboard was a relatively small, mini-fridge sized experiment known as the Advanced Plant Habitat (APH), which astronauts will use to expand their ability to grow vegetables and other plants on the station, some of which will end up on the menu. Eventually, scientists hope astronauts will be able to use the unit to grow larger and more nutrient-dense plants. But ultimately, the goal of APH and other projects like it is simply to determine the viability of plant growth in environments other than Earth in preparation for Martian expeditions, says Edward Guinan, a professor of astronomy and astrophysics at Villanova University in Pennsylvania. "To grow plants in Mars' cold climate, plants will need to be sheltered in greenhouses," Dr. Guinan tells the Monitor via email. "The amount of sunlight (solar radiation) on Mars is about 50 percent of that of the Earth since Mars is 1.5 times further than the Earth from the Sun."

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This Planet Just Outside Our Solar System Is 'Potentially Habitable'

NPR  radio


A potentially habitable planet about the size of Earth is orbiting the star that is nearest our solar system, according to scientists who describe the find Wednesday in the journal Nature. Edward Guinan, an astronomer at Villanova University, says when he first learned of this new planet a couple of months ago, he seriously doubted that it would have any chance of being habitable. That's because being close to a star means that a planet's atmosphere and any water could get blown away, as the planet is exposed to the stellar wind, flares, X-rays and ultraviolet radiation.

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Research Grants (4)

“Sun in Time Program”


The study (since 1988) of solar and stellar dynamos and magnetic evolution of the Sun and effects of resulting coronal X-ray –chromospheric UV radiation on hosted planets.Also investigating the effects of solar and stellar flares on hosted planets.

The Study of Eclipsing Binaries using Artificial Intelligence


Conducted since 2006 with co-investigators Dr. Andrej Prsa and Dr. Edward Devinney– to develop Neural Network / Artificial Intelligence Protocols for the analysis of the millions of the light curves of eclipsing binaries and variable stars expected from Kepler, PanSTARRS and big data missions such Gaia and LSST.

Living with a Red Dwarf Program

NSF, NASA/Hubble Space Telescope, NASA/Chandra and NASA/ESA XMM-Newton 

Conducted with co-investigators Scott Engle, George McCook, Richard Wasatonic, Larry DeWarf and several undergraduate students. The primary aims of this program are the study of magnetic dynamo energy generation of stars with deep convective zones and the impacts of the resulting X-ray / UV emissions, stellar winds and powerful flares on hosted planets. Just recently an Earth-size, potentially habitable planet, Proxima Cen b, was discovered orbiting the nearest red dwarf stars.

“Astrobiology: Life in Pitch Lakes and Mud Volcanoes as Analogs for Potential Life on Titan and Mars

Villanova University Faculty Support and Development Grant 

Carried out in collaboration with Dr. Dirk Schulze-Makuch (WSU) and Dr. Shirin Haque (UWI) (2010-2016). Study of biological content of a large pitch (tar) lake and mud volcanoes in southern Trinidad to determine, respectively, the biotic potential of hydrocarbon lakes on the moon Titan and the potential for life on Mars.

Select Academic Articles (5)

About Exobiology: The Case for Dwarf K Stars

The Astrophysical Journal

2016 One of the most fundamental topics of exobiology concerns the identification of stars with environments consistent with life. Although it is believed that most types of main-sequence stars might be able to support life, particularly extremophiles, special requirements appear to be necessary for the development and sustainability of advanced life forms. From our study, orange main-sequence stars, ranging from spectral type late-G to mid-K (with a maximum at early-K), are most promising. Our analysis considers a variety of aspects, including (1) the frequency of the various types of stars, (2) the speed of stellar evolution their lifetimes, (3) the size of the stellar climatological habitable zones (CLI-HZs), (4) the strengths and persistence of their magnetic dynamo generated X-ray - UV emissions, and (5) the frequency and severity of flares, including superflares; both (4) and (5) greatly reduce the suitability of red dwarfs to host life-bearing planets. The various phenomena show pronounced dependencies on the stellar key parameters such as effective temperature and mass, permitting the assessment of the astrobiological significance of various types of stars. Thus, we developed a "Habitable-Planetary-Real-Estate Parameter" (HabPREP) that provides a measure for stars that are most suitable for planets with life. Early K stars are found to have the highest HabPREP values, indicating they may be "Goldilocks" stars for life-hosting planets. Red dwarfs are numerous, having long lifetimes, but their narrow CLI-HZs and hazards from magnetic activity make them less suitable for hosting exolife. Moreover, we provide X-ray - FUV irradiances for G0 V - M5 V stars over a wide range of ages.

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The Habitability of Proxima Centauri B. I. Irradiation, Rotation and Volatile Inventory From Formation to the Present

Astronomy & Astrophysics

2016 Proxima b is a planet with a minimum mass of 1.3 MEarth orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass, active star and the Sun's closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time evolution of the star's spectrum, which is essential for modeling the flux received over Proxima b's lifetime. We also show that Proxima b's obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet's eccentricity and level of triaxiality. Next we consider the evolution of Proxima b's water inventory. We use our spectral energy distribution to compute the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find that Proxima b is likely to have lost less than an Earth ocean's worth of hydrogen before it reached the HZ 100-200 Myr after its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We conclude that Proxima b is a viable candidate habitable planet.

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The Secret Life of Cepheids: Evolution, Mass Loss, and Ultraviolet Emission of the Long Period Classical Cepheid L Carinae

Astrophysical Journal

2016 The classical Cepheid l Carinae is an essential calibrator of the Cepheid Leavitt Law as a rare long-period Galactic Cepheid. Understanding the properties of this star will also constrain the physics and evolution of massive (M≥8 M⊙) Cepheids. The challenge, however, is precisely measuring the star's pulsation period and its rate of period change. The former is important for calibrating the Leavitt Law and the latter for stellar evolution modeling. In this work, we combine previous time-series observations spanning more than a century with new observations to remeasure the pulsation period and compute the rate of period change. We compare our new rate of period change with stellar evolution models to measure the properties of l Car, but find models and observations are, at best, marginally consistent. The results imply that l Car does not have significantly enhanced mass-loss rates like that measured for δ Cephei. We find that the mass of l Car is about 8 - 10 M⊙. We present Hubble Space Telescope COS observations that also differ from measurements for δ Cep, and β Dor. These measurements further add to the challenge of understanding the physics of Cepheids, but do hint at the possible relation between enhanced mass loss and ultraviolet emission, perhaps both due to the strength of shocks propagating in the atmospheres of Cepheids.

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Living with a Red Dwarf: Rotation and X-Ray and Ultraviolet Properties of the Halo Population Kapteyn's Star

Astrophysical Journal

2016 As part of Villanova's Living with a Red Dwarf program, we have obtained UV, X-ray and optical data of the Population II red dwarf -- Kapteyn's Star. Kapteyn's Star is noteworthy for its large proper motions and high RV of ~+245 km s^-1. As the nearest Pop II red dwarf, it serves as an old age anchor for calibrating Activity/Irradiance-Rotation-Age relations, and an important test bed for stellar dynamos and the resulting X-ray -- UV emissions of slowly rotating, near-fully convective red dwarf stars. Adding to the notoriety, Kapteyn's Star has recently been reported to host two super-Earth candidates, one of which (Kapteyn b) is orbiting within the habitable zone (Anglada-Escude et al. 2014a, 2015). However, Robertson et al. (2015) questioned the planet's existence since its orbital period may be an artifact of activity, related to the star's rotation period. Because of its large Doppler-shift, measures of the important, chromospheric H I Lyman-alpha 1215.67A emission line can be reliably made, because it is mostly displaced from ISM and geo-coronal sources. Lyman-alpha emission dominates the FUV region of cool stars. Our measures can help determine the X-ray--UV effects on planets hosted by Kapteyn's Star, and planets hosted by other old red dwarfs. Stellar X-ray and Lyman-alpha emissions have strong influences on the heating and ionization of upper planetary atmospheres and can (with stellar winds and flares) erode or even eliminate planetary atmospheres. Using our program stars, we have reconstructed the past exposures of Kapteyn's Star's planets to coronal -- chromospheric XUV emissions over time.

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Magnetic Field and Wind of Kappa Ceti: Toward the Planetary Habitability of the Young Sun When Life Arose on Earth

Astrophysical Journal Letters

2016 We report magnetic field measurements for Kappa1~Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic field to derive the magnetic environment, stellar winds and particle flux permeating the interplanetary medium around Kappa1~Cet. Our results show a closer magnetosphere and mass-loss rate of Mdot = 9.7 x 10^{-13} Msol/yr, i.e., a factor 50 times larger than the current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and a hypothetical young-Earth analogue, potentially affecting the planet's habitability. Interaction of the wind from the young Sun with the planetary ancient magnetic field may have affected the young Earth and its life conditions

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