By discovering the relation between brightness and period in Cepheid variable stars (large, pulsating, luminous stars), Leavitt is responsible for one of the most astonishing breakthroughs in astronomy. Born in 1868, she was quickly recognized as a prodigy and excelled in a mathematics course at Harvard . Later, she applied for a non-paying position at Harvard's observatory, where she recorded an impressive number of variable stars. With further study, she observed that brighter stars had longer periods, which was of great importance to the study of stellar distances because their periods are related to brightness. Years later, she became the director of such an observatory, but much of her expertise was overlooked throughout her life. Only years after her death did scientists appreciate her work and the doors it opened in science. Related links: Women's History and Harvard

As the first woman to receive the Henry Draper Medal from the National Academy of Sciences, Cannon symbolizes a significant accomplishment for women in science and education. Born in 1863, she was inspired by her mother to pursue STEM studies . Cannon's mother was a significant influence on her career, motivating her to pursue mathematics and science in college. Even before completing her master's degree, Annie had published her first catalog of stars in 1901, revolutionizing how scientists classified them. Later, after being appointed curator at Harvard 's observatory, she excelled at star classification, cataloguing approximately 350,000 stars throughout her life. Related links: Women's History , Amphilsoc , and Harvard

Herschel was the first paid female astronomer. Born in 1750 in Germany, she fiercely opposed prejudice , becoming a respected scientist and an inspiration and source of motivation for other women and movements. Herschel's brother, William Herschel, taught her math so she could assist him with his astronomical work. Her many accomplishments began with helping her brother, who had discovered Uranus. Caroline, however, was responsible for many groundbreaking works, becoming a pioneer in cometary research by discovering them. Related links: RMG , ESA , and School Observatory

Since her 20s, the Puerto Rican astrophysicist has been blind . Even then, she was the first to hear a gamma-ray burst (GRB). For many years, GRB's data and graphs were restricted, making them inaccessible to someone with such a disability. Her outstanding work and persistence led to the development of a technique that converts visual data into sound. She is a strong example of the growing need for diversity and inclusion, as her innovation enabled discoveries that couldn't have been made with visual data alone. Wanda continues to advocate for greater inclusivity in the scientific community. Related links: WomenInnovations and School Observatory

As a science ambassador in NASA 's Exoplanet Exploration Program, Tripathi earned her Ph.D. in astrophysics from Harvard . She, like this website, aims to democratize science by making it more accessible. Her outstanding work and research have had a substantial impact on current exoplane t knowledge, including their formation and atmospheric loss. Tripathi's work goes beyond astrophysics, reaching climate change research and politics. Since ETastro focuses on astrophysics, if you want to learn more about her, we recommend visiting our related links or searching her name online. She is an inspiring woman and deserves proper recognition. Related links: NASA1 and NASA2

Recently, an international team, including astronomer Joseph Callingham and other UCL astronomers, made a groundbreaking observation. For the first time, we have a clear signal of a giant stellar eruption outside our Solar System. This significant burst would have devastating effects on any orbiting planets, even though it shows many similarities to processes on our Sun. Artist's impression of a coronal mass ejection around a nearby star. Copyright and credit to Olena Shmahalo/Callingham et al. What is it, and how was it discovered The Observatoire de Paris-CNRS and ASTRON (Netherlands Institute for Radio Astronomy) captured short and intense bursts of radio waves near a red dwarf star. They then noticed that such bursts were similar to our Sun's Coronal Mass Ejection (CME), which are large eruptions of magnetized plasma from stars that play an important role in shaping Earth's weather and even creating the auroras we see. This news becomes prominent because it supports a long-standing theory that the CME process also occurs in stars beyond our solar system. Planets and Red Dwarfs Planets with mass similar to Earth's are most commonly found orbiting red dwarfs, stars with 10-50% our Sun's mass. Due to the planet's proximity to the star, its habitable zone (where there can be liquid water on the planet's surface, not turning into gas or solid) is quite close to the star itself, making it especially vulnerable to stellar storms. This study shows that violent space weather isn't unique to the Sun but occurs in stars beyond our system. Importance This news has major implications for the study of planetary habitability, suggesting that some planets may be too close to highly active stars to support life. This discovery also raises questions about whether such a process is common to all red dwarfs and increases the study of stellar eruptions and their effects on a planet's lifespan. Related links: Leiden University:   https://www.universiteitleiden.nl/en/news/2025/11/evidence-of-a-massive-stellar- storm-on-a-nearby-star?utm_source=chatgpt.com UCL news: https://www.ucl.ac.uk/news/2025/nov/evidence-massive-stellar-storm-nearby-star Paris Observatory: https://observatoiredeparis.psl.eu/evidence-of-a-massive-stellar.html

In 1971, Paul Murdin and Louise Webster made a groundbreaking discovery; they were the first to identify a black hole, which had already been detected but not yet classified. Their analysis has led to the identification of many other black holes, and, later in 2019, to their capture as images. But what is a black hole(BH)? Image credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman Concept With huge densities, great mass concentrated in a tiny region, black holes have extreme gravity to a point that nothing, not even light, can escape them, its gravity taking over any other possible forces. As light can't escape its boundary, called the event horizon (the point where gravity overcomes everything, so nothing past it can escape), the BH is considered to be invisible.  Types Depending on its size, BHs can be considered to be of different types: stellar mass, supermassive, or intermediate. The most common ones are stellar-mass black holes, which form from the death of large stars that run out of fuel and are unable to continue nuclear fusion (which provides a force that counteracts gravity, preventing the star from collapsing in on itself). Supermassive Black Holes (SMBH) aren't the most common, but they are present at the center of nearly every galaxy, including our own. Their origin remains a mystery, as they're too massive (100k to billions of times the mass of our Sun) to have formed from a single star. Intermediate BHs are even less well known, as we have seen few; their masses range from 100 to 10k times that of the Sun, placing them between the previous types, with size being the only currently available information. Observing BHs Since BHs are considered invisible, since light can't escape the event horizon, scientists began observing them indirectly, through orbiting bodies, gas, and matter. Due to the intense gravity of the BH, matter pulled by it reaches such high velocities that it becomes heated and emits radiation, allowing us to detect it with telescopes. Another way of “seeing” BHs is to notice unusual behaviours in stars around regions of space that appear empty but actually contain black holes. We now have many methods for detecting such interesting bodies; these analyses are only a few examples. Other facts Black Holes are determined by only two quantities, their mass and the speed at which they spin. Their mass is related to how compact they become, since their huge mass is ‘held’ in such a small space, thereby increasing their gravitational force. It is also related to the fact that the smaller it is, the faster it spins. Even with its powerful gravitational pull, it doesn't behave like an uncontrolled vacuum, consuming anything that passes by; bodies orbit it and normally fall in only under external perturbations. Black holes are messy eaters, as most of what falls into them is ejected outwards because the object is being ripped apart, so matter can be flung off in the process. What is then jetted away, commonly called “winds”, has either a positive or a negative effect on star formation, playing a significant role in a galaxy's lifespan.   Related links: UChicago: https://news.uchicago.edu/explainer/black-holes-explained Harvard: https://www.cfa.harvard.edu/research/topic/black-holes ESA: https://www.esa.int/Science_Exploration/Space_Science/Black_holes

In the late 1960s, extensive technological development occurred in the US and the Soviet Union as they competed and rushed to advance. In the midst of that, while on the lookout for Soviet nuclear testing, US military telescopes captured the most energetic form of light burst in the universe. Now known as "gamma-ray bursts” or GRBs. The process is directly related to black holes. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab What are these bursts? A gamma-ray is the most energetic form of light. So, GRBs are considered the brightest explosions in the universe. Their duration is short, but they emit unimaginable amounts of light. They shine hundreds of times brighter than a supernova, and expel more energy than our Sun will throughout its complete life. They appear to be associated with galaxies with high stellar formation ages, which wouldn't be representative of our current Milky Way. Nonetheless, about 2 billion years ago, our host galaxy could have been home to such processes. Their light emission, like that of pulsars, occurs similarly to that of lighthouses, channeling energy through 2 narrow beams. GRBs types Their classification depends entirely on their duration: long- and short-duration. The origin of those different classes may not be the same, but the creation of a new black hole seems to be the outcome of both. Long-duration:  this class accounts for most GRBs (about 70%) and lasts from 2 to hundreds of seconds. Its origin is related to the death of massive stars. The starting mass of the star is 5 to 10 times that of our Sun, and once it runs out of fuel to sustain nuclear fusion, it explodes into a supernova and creates a black hole. A GRB occurs when a newly born black hole begins to accrete surrounding matter, thereby strengthening its magnetic field. It then blasts out two gamma-ray jets at nearly the speed of light.  Short-duration:  lasting less than 2 seconds, this class originates from the merger of 2 black holes or a black hole and a neutron star. Those bodies must have been in a binary system for some time prior to the collapse. The resulting impact ejects the neutron star's matter, triggering a GRB. The binary system containing two black holes, on the other hand, wouldn't expel matter. How can it produce a GRB? That is a question that scientists have not yet answered, and that requires ongoing research. Related links: ESO: https://www.eso.org/public/science/grb/ NASA: https://imagine.gsfc.nasa.gov/science/objects/bursts1.html https://science.nasa.gov/mission/hubble/science/science-behind-the-discoveries/hubble- gamma-ray-bursts/ SPACE.com : https://www.space.com/gamma-ray-burst.html BBC: https://www.skyatnightmagazine.com/space-science/what-is-a-gamma -ray-burst

Volcanoes on Earth can be dangerous; they remain dormant for years and can erupt unexpectedly. Recently, however, a similar process occurred in the universe. A black hole, located at the center of the galaxy J1007+3540, that hadn't had any activity for 100 million years, suddenly erupted. Not only that, but instead of being a smaller stellar black hole, it was a supermassive black hole. Image of J1007+3540, with a bright inner jet, representing the reactivation of a past dormant black hole. Copyright and credit to LOFAR, Pan-STARRS, S. Kumari et al. Supermassive Black Hole (SMBH)  Living at the center of most known galaxies, those black holes are millions and billions of times the mass of our sun. They can be quiet or actively feeding and violent, the latter have clouds of matter surrounding them that "feed” them, commonly called “accretion disk”. This part, due to the intense gravitational force that generates friction on the surrounding matter and gas, heats up and glows. Some of the mass on the accretion disk is channeled from the magnetic field to the poles of the SMBH. It is then emitted as jets at nearly the speed of light, becoming bright and reaching vast distances. Erupting SMBHs are also called Active Galactic Nuclei (AGN). Galaxy J1007+3540  The galaxy became a subject of study when astronomers observed its unusual "footprint". Such a large structure with jet activity, indicated by plasma lobes, isn't unusual; what is unusual is that there was a smaller, brighter jet within the other normal jets. That suggests that the AGN had returned to activity, as scientists compare it to a switch being turned on and off. This system, composed of two very large cosmic structures, facilitates astronomical analysis. Analyzing jets Scientists seek evidence of past active phases of AGNs, such as ionized gas that has traveled far from the galaxy's center. The radio images of J1007+3540 provide evidence of both the active phase, with a newborn jet, and the dormant phase, with surrounding older material from previous blasts.   Environmental effect   It is well established that AGN jets affect the intracluster medium (the region between galaxies, filled with superheated gas), but the details of their impact remain unclear. This recent eruption, however, provided insight into that problem: the material from the jet, after interacting with the hot gas, was bent and distorted non-uniformly, with some jets compressed and others elongated. Related links: Scientific American:   https://www.scientificamerican.com/article/back-from-the-dead-a-black-hole-is- erupting-after-a-100-million-year-hiatus/ Space.com : https://www.space.com/astronomy/black-holes/reborn-black-hole-seen-erupting-across-1- million-light-years-of-space-like-a-cosmic-volcano LiveScience: https://www.livescience.com/space/black-holes/like-watching-a-cosmic-volcano-erupt- scientists-see-monster-black-hole-reborn-after-100-million-years

Born in 1943, the renowned astrophysicist Burner has advanced our understanding of neutron stars. The British Ph.D. scientist, at 24, captured the first evidence of a pulsar in 1967. The Nobel Prize was awarded to her male supervisor for the discovery, reflecting the era's prejudice that remains evident today.  Throughout her distinguished career, she has served as a Professor at the University of Oxford and as President of the Institute of Physics . Through this, she has been an example of the need for diversity , a commitment she continues to advocate for in science, confident that it improves research. Related links: IOP and University of Cambridge

In 1992, scientists made a groundbreaking discovery. They captured the existence of a planet outside the Solar System, an exoplanet. To determine whether life could exist beyond Earth, research began. Currently, more than 6,000 exoplanets have been documented, most of which are in the Milky Way. Still, astrophysicists are confident there are way more than we can currently see. Exoplanet Proxima Centauri b (closest exoplanet to Earth): artist's conception image copyright and credit to ESO/M. Kornmesse How are exoplanets like Exoplanets can take up a significant branch of appearances, some similar to Mercury, others to Neptune, and some nothing like any planet in our Solar System. There are four main types: Gas giants, Neptunian planets, terrestrial planets, and super-Earths.  Gas giants are at least as large as Saturn, though some can be much larger. Neptunian planets are similar in size to Neptune or Uranus and have rocky cores and outer atmospheres composed of hydrogen and helium. Terrestrial planets are Earth-sized or smaller, composed of rock, silicate, water, or carbon. Super-Earths are larger than Earth, but lighter than Neptune, and may or may not have an atmosphere.  How do we find them Can you see it with your usual home telescope? No. Exoplanets are far too small to be directly seen. To overcome that issue, scientists use other methods, the most common being transit and radial velocity. Transit is used when a planet passes directly “in front” of the star it orbits (from our perspective). The detection of some of the star's light being blocked is enough of a clue to raise suspicion of the existence of an exoplanet. Radial velocity concerns the planet's effect on the star's light. The planet's gravitational pull affects the star's light spectrum. So, when an exoplanet orbits a star, it changes the color of the light received by astronomers. Why study exoplanets The discovery of exoplanets has dramatically expanded our understanding of planets, from their formation to their potential to host life. We haven't yet found signs of life in any of them. Still, that discovery would drastically change our perception of the future and of our past. So, keeping that study alive is essential, even more so nowadays, given the climate conditions we face. How can we know if a planet has the conditions to hold life?  First, an exoplanet must be located in a "habitable zone”, or Goldilocks zone: the region where water can remain in its liquid state in the planet's atmosphere. It has all to do with being placed at an adequate distance from its orbiting star. That, however, isn't enough to hold life. Most planets are habitable because of extreme conditions beyond Earth's – temperatures and atmospheres are examples. Not only that, but rotation and radiation from stars also play a substantial role in habitability. In summary, the possibility of raising life on other planets remains a challenge for many scientists due to the stringent requirements. Related Links: Nasa:   https://science.nasa.gov/exoplanets/ Planetary.org :   https://www.planetary.org/worlds/exoplanets Uchicago:   https://news.uchicago.edu/explainer/exoplanets-explained

In 1967, Jocelyn Bell detected the first evidence of what we now consider to be the most dense object known — a neutron star. A star's fate is almost predetermined by its initial size. So, how big is a star to generate a neutron star? How or why does it become so dense? Black Hole (left) and neutron star (right): artist's conception of a black hole orbited by a cracked neutron star.  Copyright and credit to Caltech/R. Hurt (IPAC). Neutron star formation  Stars about 8 times the mass of the Sun die faster because their higher rate of nuclear fusion resists the gravitational force. Once it consumes all its fuel, it collapses in on itself, and the star explodes into a supernova. If the remaining core has a mass of approximately 1-3 solar masses, it will collapse to a neutron star. A body with the same composition as an atom's nucleus. But that's not what truly makes them interesting. What scientists are impressed by is its mass-radius relation and its density. For reference, our Sun has a radius of almost 700,000 km. And, with only a 10 km radius, a neutron star holds a mass greater than our Sun's. How do we find them Neutron stars have high temperatures even though they don't undergo nuclear fusion. Much of their energy comes from the supernova they underwent. The surface eventually cools, but sufficiently high temperatures allow scientists to observe the star using X-ray telescopes.  That is just an example; however, their observed wavelengths vary with their state or classification (each of which is explained in the sections below). A neutron star can be found in binary systems– partnered with ordinary or other neutron stars–, as pulsars, or as magnetars. The three "formats” are most commonly found, respectively, via X-rays, radio signals, and gamma rays. Binary systems In case it is paired with an ordinary star, the powerful gravitational force of the neutron star causes it to accrete material from the partner. In other words, it can strip/pull matter from the other star's surface. That material is then pulled towards the neutron star due to its magnetic field. Simultaneously, the elements being drawn are heated to the point of radiating X-rays, which are subsequently detected by telescopes.  There is also the chance of a binary composed of two different neutron stars. The type of binary system, however, does not change the fact that, in the event of a collision, they generate "kilonovas". So, if a neutron star and its stellar partner collapse due to their gravity, they produce short-duration gamma-ray bursts (kilonova). An event that is powerful enough to begin nuclear fusion, which leads to heavier elements (reaching gold) than those seen in usual stellar processes (reaching iron). Pulsars and Magnetars Most neutron stars are what is called a “pulsar”. The name derives from their constant rotation and the emission of radiation at regular intervals. Similar to what is seen in a lighthouse. Pulsars have strong magnetic fields that, in the form of two jets, channel particles/matter. Because of that, what we see are flashes of light captured when that jet is funneled in our direction. On the other hand, magnetars are simply neutron stars with extreme magnetic fields. While a normal neutron star would have a magnetic field about a trillion times Earth's, a magnetar's is 1000 times stronger. Related links: Nasa: https://imagine.gsfc.nasa.gov/science/objects/neutron_stars1.html https://imagine.gsfc.nasa.gov/science/objects/neutron_stars2.html ESA: https://esahubble.org/wordbank/neutron-star/ Harvard: https://www.cfa.harvard.edu/research/topic/neutron-stars-and-white-dwarfs