Tag: astronomy

See the Perseids and Southern Delta Aquariids in a Stunning Double Meteor Shower

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Get ready to see a double meteor shower featuring one of the biggest and brightest meteor showers of the year, the Perseids! In addition to the Perseids, the Southern Delta Aquariids continue to be active in August while the Perseids peak, creating a double meteor shower that those in the northern hemisphere will be able to enjoy in all its glory. (It might be difficult, though not impossible, for those in the southern hemisphere to see some Perseids and thus the double shower; the Southern Delta Aquariids, however, will be more prominent in the southern than in the northern hemisphere.) Here’s everything you need to know to watch this stunning display.

How to watch a meteor shower

To see the most meteors, you’ll want to watch with a clear, dark sky, in a place that’s away from sources of light. Moonlight can wash out the light from meteors, so observing conditions are best when there’s very little to no moonlight.

If you need a small amount of light to see where you’re going, use a red light instead of a white light. Unlike red light, white light disrupts your night vision, or your ability to see objects in the dark—including meteors. Using a red light means you won’t have to wait for your vision to readjust to the dark.

You don’t need any special equipment like binoculars or telescopes. Using your naked eye is actually the best way to watch a meteor shower because you need to be able to observe the whole sky to see the most meteors possible—telescopes and binoculars aren’t ideal for observing meteor showers because they limit your field of view, and meteors move too quickly to find them in the lens of your equipment.

Meteor showers are named after their radiant, or the constellation that the meteors appear to radiate from. (Apps like Stellarium or SkyView can be useful in finding these.) To see a meteor shower, you don’t need to look directly at the radiant, but you will want to make sure that the radiant is above the horizon, which usually happens around midnight or later.

You will be able to see the most meteors when the radiant is at its highest point in the sky, but this is not necessary to enjoy a meteor shower.

The Southern Delta Aquariids

The Southern Delta Aquariids produce about 15-20 meteors per hour. These meteors aren’t as bright as the Perseids, but this meteor shower is still an awe-inspiring event that you won’t want to miss.

The Southern Delta Aquariids are active from July 18 to August 21. Unlike many meteor showers, the Southern Delta Aquariids don’t have a sharp peak; in other words, the number of meteors steadily increases while the meteor shower is active. This means that you will be able to see some Southern Delta Aquariids during the peak of the Perseid meteor shower in mid-August!

Fortunately, moonlight won’t be an issue in the first half of August. Until the night of August 11-12, when the Perseids peak, the moon will transition from a waning crescent (12 percent full) to a new moon (0 percent full) to a waxing crescent (35 percent full) to, finally, a first quarter moon (44 percent full). However, from the beginning of August until around August 14, the moon will set before or shortly after midnight local daylight time, creating perfect observing conditions.

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August 4, 2024
Get ready to watch the dazzling Perseid meteor shower in August

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One of the highlights of the astronomical calendar, and something I look forward to every year, is the Perseid meteor shower. This impressive display, which is visible in the northern and parts of the southern hemisphere, will peak on the evening of 12 August, running into the early hours of 13 August. What makes it special is that, at least where I am in the northern hemisphere, it tends to happen on a warm evening – unlike the equally spectacular Geminids in December.

The number of meteors you can expect to see during the Perseids varies depending on light pollution,…

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July 31, 2024
Three potentially habitable super-Earths found by astronomers

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An international team of researchers have discovered three potentially habitable super-Earth exoplanets orbiting a relatively nearby orange dwarf star.

The three super-Earths are orbiting Star HD 48498, located approximately 55 light-years from Earth.

The team, led by Dr Shweta Dalal from the University of Exeter, found that the orange star is somewhat similar to our Sun.

This discovery is the closest planetary system to host a Super-Earth in the habitable zone around a Sun-like star.

The work is published in the journal MNRAS.

The super-Earth exoplanets could potentially support life

The three super-Earths orbit their host star in seven, 38, and 151 Earth days, respectively.

Remarkably, the outermost exoplanet candidate lies within the habitable zone of its star, where conditions might permit liquid water to exist without boiling or freezing.

This area, commonly known as the Goldilocks zone, is deemed ideal for potentially supporting life.

Dr Dalal said: “The discovery of this Super-Earth in the habitable zone around an orange star is an exciting step forward in our quest to find habitable planets around solar-type stars.”

The super-Earths were identified using HARPS-N Rocky Planet Search programme

Over a decade, the team collected nearly 190 high-precision radial velocity measurements using the HARPS-N spectrograph.

Radial velocity measurements track the star’s subtle movements caused by orbiting planets.

These measurements are important in exoplanet discoveries.

By analysing the spectrum of light from the star, researchers can determine whether it is moving towards us (blueshift) or away from us (redshift).

The system is a promising target for high-contrast imaging

The researchers identified three planetary candidates with minimum masses between five and 11 times that of Earth.

The team proposed that the star’s proximity, along with the favourable orbit of the outermost planet, makes this system an excellent target for future high-contrast direct imaging and high-resolution spectroscopic studies.

Future discovery of habitable super-Earth exoplanets

Dr Dalal concluded: “This discovery highlights the importance of long-term monitoring and advanced techniques in uncovering the secrets of distant star systems. We are eager to continue our observations and look for additional planets in the system.”

The discovery will pave the way for understanding the potential for life beyond our solar system.

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June 25, 2024
What Came Before the Big Bang?

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Robert Brandenberger, a physicist at McGill University who was not involved with the study, said the new paper “sets a new standard of rigor for the analysis” of the mathematics of the beginning of time. In some cases, what appears at first to be a singularity—a point in space-time where mathematical descriptions lose their meaning—may in fact be an illusion.

A Taxonomy of Singularities

The central issue confronting Geshnizjani, Ling, and Quintin is whether there is a point prior to inflation at which the laws of gravity break down in a singularity. The simplest example of a mathematical singularity is what happens to the function 1/x as x approaches zero. The function takes a number x as an input, and outputs another number. As x gets smaller and smaller, 1/x gets larger and larger, approaching infinity. If x is zero, the function is no longer well defined: It can’t be relied upon as a description of reality.

“We mathematically showed that there might be a way to see beyond our universe,” said Eric Ling of the University of Copenhagen.

Photograph: Annachiara Piubello

Sometimes, however, mathematicians can get around a singularity. For example, consider the prime meridian, which passes through Greenwich, England, at longitude zero. If you had a function of 1/longitude, it would go berserk in Greenwich. But there’s not actually anything physically special about suburban London: You could easily redefine zero longitude to pass through some other place on Earth, and then your function would behave perfectly normally when approaching the Royal Observatory in Greenwich.

Something similar happens at the boundary of mathematical models of black holes. The equations that describe spherical nonrotating black holes, worked out by the physicist Karl Schwarzschild in 1916, have a term whose denominator goes to zero at the event horizon of the black hole—the surface surrounding a black hole beyond which nothing can escape. That led physicists to believe that the event horizon was a physical singularity. But eight years later the astronomer Arthur Eddington showed that if a different set of coordinates is used, the singularity disappears. Like the prime meridian, the event horizon is an illusion: a mathematical artifact called a coordinate singularity, which only arises because of the choice of coordinates.

At a black hole’s center, by contrast, the density and curvature go to infinity in a way that can’t be eliminated by using a different coordinate system. The laws of general relativity start spewing out gibberish. This is called a curvature singularity. It implies that something is taking place that’s beyond the ability of current physical and mathematical theories to describe.

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June 23, 2024
Astronomers witness massive black hole awaken in real-time

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Astronomers are witnessing changes never seen before in a galaxy — likely the result of the sudden awakening of a massive black hole at its core.

In late 2019, the previously unremarkable galaxy SDSS1335+0728 started shining brighter, which was believed to be caused by a massive black hole.

To understand why, astronomers have used data from several space and ground-based observatories, including the European Southern Observatory’s Very Large Telescope, to track how the galaxy’s brightness has varied.

“Imagine you’ve been observing a distant galaxy for years, and it always seemed calm and inactive,” said Paula Sánchez Sáez, an astronomer at ESO.

“Suddenly, its core starts showing dramatic changes in brightness, unlike any typical events we’ve seen before.”

The brightness is unlike anything we’ve witnessed before

SDSS1335+0728 is now classified as having an ‘active galactic nucleus’ (AGN) – a bright, compact region powered by a massive black hole – after it brightened dramatically.

Some phenomena, like supernova explosions or tidal disruption events – when a star gets too close to a black hole and is torn apart – can suddenly light up galaxies.

But these brightness variations typically last only a few dozen or, at most, a few hundred days. SDSS1335+0728 is still growing brighter today, more than four years after it was first seen to ‘switch on’.

Moreover, the variations detected in the galaxy, which is located 300 million light-years away in the constellation Virgo, are unlike any seen before, pointing astronomers towards a different explanation.

How massive black holes grow and evolve

The team tried to understand these brightness variations using a combination of archival data and new observations from several facilities, including the X-shooter instrument on ESO’s VLT in Chile’s Atacama Desert.

Comparing the data taken before and after December 2019, they found that SDSS1335+0728 is now radiating much more light at ultraviolet, optical, and infrared wavelengths.

Lorena Hernández García, co-author of the study, explained: “The most tangible option to explain this phenomenon is that we are seeing how the core of the galaxy is beginning to show activity.

“If so, this would be the first time that we see the activation of a massive black hole in real-time.”

Previous studies reported inactive galaxies becoming active after several years, but this is the first time the awakening of the black hole has been observed in real-time.

Claudio Ricci, another co-author of the study, commented: “In the case of SDSS1335+0728, we were able to observe the awakening of the massive black hole, which suddenly started to feast on gas available in its surroundings, becoming very bright.”

This is a process that has never been observed before.

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June 19, 2024
Cosmic cloud exposed Earth to interstellar space 3 million years ago

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Illustration of the protective bubble around the sun (yellow dot) and Earth (blue dot)

Harvard Radcliffe Institute

Between 2 million and 3 million years ago, the solar system encountered turbulence on a galactic scale, colliding with a dense interstellar cloud that may have altered both the climate and evolution on Earth.

Researchers have only recently been able to map the path of the sun through our galaxy, particularly in relation to the relatively dense hydrogen clouds that also journey through the interstellar medium, the vast space between star systems.

Now, a team led by Merav Opher at Boston University in Massachusetts has uncovered evidence that one of these clouds, the Local Ribbon of Cold Clouds in the constellation Lynx, probably crossed paths with our sun’s heliosphere.

The heliosphere is a protective cocoon or bubble formed by solar winds pushing out to the edges of the solar system. Inside the heliosphere, planets are protected from the worst of the galaxy’s gamma radiation.

The new study proposes that as the solar system passed through the interstellar cloud, the heliosphere retreated from it, moving inwards towards the sun. The researchers think the heliosphere shrunk so far that Earth was outside the protective cocoon provided by the solar winds, possibly for as long as 10,000 years.

Using the European Space Agency’s Gaia Satellite, Merav and her colleagues mapped the location of the dense cold cloud and the past trajectory of the sun.

Opher says the probable encounter between the heliosphere and the cold cloud aligns with the deposition of the elements plutonium-244 and radioactive iron-60 in Antarctic ice, deep ocean cores and lunar samples. These elements, which originated in distant supernovae, are captured within interstellar clouds and were probably deposited on Earth while it was outside the heliosphere.

“The indication of an increase in these elements around 2 [million] to 3 million years ago gives us compelling evidence that indeed the sun crossed that cloud around 2 million years ago,” says Opher. “The Earth’s exposure to cold interstellar medium clouds and the related massive increase of hydrogen in the atmosphere and increased radiation almost certainly had a substantial impact on our planet and its climate.”

Sarah Spitzer at the University of Michigan says the paper provides “compelling” evidence that the heliosphere was exposed to a much denser interstellar cloud 2 million to 3 million years ago. The result of the solar system passing through that dense cold cloud was that Earth would have been outside the heliosphere and directly exposed to the interstellar environment, she says.

“Understanding this helps us learn about the effects of the interstellar medium on life on Earth in the past,” says Spitzer. “But it also helps us better understand the current effects of the heliosphere on life on Earth, what might happen if the Earth is exposed to the interstellar medium again in the future, and when that might happen.”

Evan Economo at the Okinawa Institute of Science and Technology in Japan says it is intriguing to think about how encounters in “our local cosmic neighbourhood” may have affected the environment experienced by life on Earth.

“The heliosphere is part of the extended environment that organisms experience on the surface of the Earth, affecting climate and incoming radiation from space,” he says. “If we were outside the heliosphere for certain periods, this could have changed the evolutionary trajectories of a broad range of organisms, including humans. Such links are highly speculative at this point, but give us a new research direction.”

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June 10, 2024
‘Unluckiest star’ may be trapped in deadly dance with a black hole

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Illustration of a black hole ripping gas from a star

Stocktrek Images/Alamy

A star appears to be locked in a lethal dance with a supermassive black hole. According to a team of astronomers, this unlucky star gets almost torn apart each time its orbit swings past the black hole on a tight loop. If they are right, we might see it happen again two years from now.

If a star gets close enough to a supermassive black hole at the centre of a galaxy, it can be tidally disrupted, which means the black…

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May 30, 2024
Why Are We Seeing These Crazy Northern Lights?

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The aurora borealis is usually visible only way up north, but two weeks ago the night sky was filled with shimmering curtains of pink and green light that could be seen all the way down into the southern US. People in Texas and Hawaii got out of their cars to stare and take pictures.

The cause of this light show was an especially strong blast of solar wind—electrically charged particles shot out from the sun at incredible speeds. And there’s more to come as we approach the peak of the current solar cycle, a period of increased solar storms that happens every 11 years.

This is one example of what scientists call “space weather,” which deals with the interaction between the sun and the Earth. Not all the consequences of space weather are pretty, and some are outright dangerous. But the physics behind it are pretty cool. Let’s check it out!

Blowin’ in the Wind

You might think of the sun as a great ball of fire—but it’s not. (Fire is a chemical reaction between oxygen and carbon.) What the sun is, really, is a giant nuclear fusion reactor. In the core, protons are smashed together under extreme pressure. These protons stick together to create the nucleus of a helium atom, with two protons and two neutrons. (Two of the protons decay into neutrons).

Illustration: Rhett Allain

But wait! The helium nucleus has less mass than the four protons we started with. That mass isn’t lost—it’s turned into energy, according to Einstein’s famous equation E = mc², where E is energy, m is mass, and c is the speed of light. That last number is huge—light travels at 300,000 kilometers per second, and it’s hugeness is squared—which means that even a tiny loss of mass creates A LOT of energy. That’s why the sun is so hot, with a core temperature of 27 million degrees Fahrenheit. Yep, that’s pretty hot.

Under this extreme heat, the gases in the outer part of the sun form a plasma in which electrons are ripped away from their atoms, leaving free electrical charges (mostly electrons and protons) zooming around. Some of them are moving fast enough to escape the gravitational pull of the sun. These ejected particles are what we call the “solar wind.”

You can see the effect of the solar wind when it hits a comet. Comets are basically big dirty snowballs that orbit the sun in long ellipses. As one nears the sun, its icy body sublimates and turns into a gas. Some of this gas gains enough energy to be ionized (electrons are freed from the atoms), leaving an electrically charged gas. Then, when the solar wind hits, it pushes this ionized gas away, creating a tail that can be tens of millions of miles long.

Fun fact: You might think the tail extends out behind the comet like a jet contrail, but it doesn’t! It extends away from the sun—so basically sideways to the direction of the comet’s motion.

Why Now?

But what causes the solar wind to get so worked up every 11 years? Well, like Earth, the sun has a magnetic field, but it’s extremely unstable. Because the sun is not a solid object, different parts of it rotate at different speeds. This causes its magnetic field to twist and warp, and every 11 years or so it actually flips and reverses polarity. This last happened in 2013, and here we are in 2024.

These moving magnetic field lines can break through the surface, creating sun spots and awesome geysers of plasma known as solar flares. Why does this happen? When electrical charges are zipping around, they can be pushed and pulled by a magnetic field. You can see this yourself with some copper wire and a battery. If you place the wire near a stationary magnet and then connect the ends so a current flows, the wire will move. Check it out:

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May 24, 2024
Amazing new images of galaxies and nebulae caught by Euclid telescope

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Euclid’s image of the star-forming region Messier 78

Messier 78 ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence

The Euclid space telescope team has released its first science images. They show sparkling clusters of galaxies, an astonishingly sharp image of a nearby spiral galaxy and a colourful cloud of interstellar gas that is home to hundreds of thousands of young stars.

The above picture shows a star-forming region called Messier 78. Euclid is so much more sensitive than previous telescopes that it revealed more than 300,000 new objects in this image alone, most of them newborn stars. Some of those objects are also rogue planets, which float around on their own rather than orbiting stars. They were previously impossible to spot in this area.

The next two images, below, are clusters of galaxies called Abell 2390 and Abell 2764. Many of Euclid’s future observations will show clusters like these – one of the telescope’s main goals is to map the cosmos’ dark matter, and the way that light from distant galaxies warps as it travels past these clusters is one way to spot dark matter’s gravitational effects.

Euclid’s view of Abell 2390

ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence.

Euclid’s view of a bright star near Abell 2764

ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence

Euclid also took images of individual galaxies within clusters, like the two shown in the image below. These galaxies are part of the Dorado group, and they are in the midst of a complex dance of hurtling past one another and eventually merging.

Euclid’s image of the Dorado group of galaxies

ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence.

The last picture of the set, below, is an enormous spiral galaxy called NGC 6744. Detailed images like this will allow researchers to study galaxy formation in exquisite detail – they have already used the Euclid data to spot a never-before-seen dwarf galaxy orbiting NGC 6744.

Euclid’s image of spiral galaxy NGC 6744

ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO or ESA Standard Licence

These five images, along with 12 others that haven’t yet been fully analysed, were all taken in only 24 hours of observation time. “At completion of the mission, the Euclid sky map will be the most detailed picture of the sky ever, so basically this gives you a hint of the observatory’s capability,” says Roland Vavrek, a member of the Euclid team at the European Space Agency. “If all this comes out of one day, it says how much data will come out of the mission over six years.”

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May 23, 2024
Astronomers using AI to prepare for ton of data from new telescopes

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It’s a problem that will be repeated in other places over the coming decade. As astronomers construct giant cameras to image the entire sky and launch infrared telescopes to hunt for distant planets, they will collect data on unprecedented scales.

“We really are not ready for that, and we should all be freaking out,” says Cecilia Garraffo, a computational astrophysicist at the Harvard-Smithsonian Center for Astrophysics. “When you have too much data and you don’t have the technology to process it, it’s like having no data.”

In preparation for the information deluge, astronomers are turning to AI for assistance, optimizing algorithms to pick out patterns in large and notoriously finicky data sets. Some are now working to establish institutes dedicated to marrying the fields of computer science and astronomy—and grappling with the terms of the new partnership.

In November 2022, Garraffo set up AstroAI as a pilot program at the Center for Astrophysics. Since then, she has put together an interdisciplinary team of over 50 members that has planned dozens of projects focusing on deep questions like how the universe began and whether we’re alone in it. Over the past few years, several similar coalitions have followed Garraffo’s lead and are now vying for funding to scale up to large institutions.

Garraffo recognized the potential utility of AI models while bouncing between career stints in astronomy, physics, and computer science. Along the way, she also picked up on a major stumbling block for past collaboration efforts: the language barrier. Often, astronomers and computer scientists struggle to join forces because they use different words to describe similar concepts. Garraffo is no stranger to translation issues, having struggled to navigate an English-only school growing up in Argentina. Drawing from that experience, she has worked to put people from both communities under one roof so they can identify common goals and find a way to communicate.

Astronomers had already been using AI models for years, mainly to classify known objects such as supernovas in telescope data. This kind of image recognition will become increasingly vital when the Vera C. Rubin Observatory opens its eyes next year and the number of annual supernova detections quickly jumps from hundreds to millions. But the new wave of AI applications extends far beyond matching games. Algorithms have recently been optimized to perform “unsupervised clustering,” in which they pick out patterns in data without being told what specifically to look for. This opens the doors for models pointing astronomers toward effects and relationships they aren’t currently aware of. For the first time, these computational tools offer astronomers the faculty of “systematically searching for the unknown,” Garraffo says. In January, AstroAI researchers used this method to catalogue over 14,000 detections from x-ray sources, which are otherwise difficult to categorize.

Another way AI is proving fruitful is by sniffing out the chemical composition of the skies on alien planets. Astronomers use telescopes to analyze the starlight that passes through planets’ atmospheres and gets soaked up at certain wavelengths by different molecules. To make sense of the leftover light spectrum, astronomers typically compare it with fake spectra they generate based on a handful of molecules they’re interested in finding—things like water and carbon dioxide. Exoplanet researchers dream of expanding their search to hundreds or thousands of compounds that could indicate life on the planet below, but it currently takes a few weeks to look for just four or five compounds. This bottleneck will become progressively more troublesome as the number of exoplanet detections rises from dozens to thousands, as is expected to happen thanks to the newly deployed James Webb Space Telescope and the European Space Agency’s Ariel Space Telescope, slated to launch in 2029.

Processing all those observations is “going to take us forever,” says Mercedes López-Morales, an astronomer at the Center for Astrophysics who studies exoplanet atmospheres. “Things like AstroAI are showing up at the right time, just before these faucets of data are coming toward us.”

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May 20, 2024