11 Fascinating Facts About Our Milky Way Galaxy


Post 8796

11 Fascinating Facts About Our Milky Way Galaxy

https://www.livescience.com/63847-facts-about-the-milky-way.html
By Adam Mann October 16, 2018

Our Milky Way Galaxy

milky way galaxy

(Image credit: ESA/NASA/JPL-Caltech)

How much do you know about the city you live in? Sure, you’ve got your favorite restaurants and the best way to avoid traffic during rush hour, but it’s unlikely you know the details of every urban nook and cranny. The same goes for the galaxy you live in, the Milky Way.

Our celestial home is an awe-inspiring place full of stars, supernovas, nebulas, energy and dark matter, but many aspects of it remain mysterious, even to scientists. For those seeking to better know their own place in the universe, here are 11 enlightening facts about the Milky Way.

The MIlky Way’s name is ancient

milky way galaxy

(Image credit: Universal History Archive/UIG via Getty)

Before the advent of electric lights, everybody on Earth had an unobstructed view of the night sky. The enormous milky band of stars crossing it was impossible to miss. Ancient peoples gave different names to the cloud-like structure of our galaxy, but our modern version derives from the Greeks, who had a myth about the infant Hercules being brought to the goddess Hera, who nursed him while she was asleep. When she awoke and pulled away, her breast milk spilled across the heavens. The source of the Greek name itself has been lost to the ages, Matthew Stanley, a professor of the history of science at the Gallatin School of Individualized Study at New York University, previously told Live Science. “It’s one of those terms that’s so old that its origin is generally forgotten by now.”

We’re not sure exactly how many stars are in the Milky Way

milky way galaxy

(Image credit: Two Micron All-Sky Survey)

Counting stars is a tedious business. Even astronomers argue over the best way to do it. Their telescopes see only the brightest stars in our galaxy, and many are hidden by obscuring gas and dust. One technique to estimate the stellar population of the Milky Way is to look at how fast stars are orbiting within it, which gives an indication of the gravitational tug, and therefore the mass, of the galaxy. Divide the galactic mass by the average size of a star and you should have your answer. But as David Kornreich, an astronomer at Ithaca College in New York, told Live Science’s sister site Space.com, these numbers are all approximations. Stars vary widely in size, and many assumptions go into estimating the number of stars residing in the Milky Way. The European Space Agency’s Gaia satellite has mapped the location of 1 billion stars in our galaxy, and its scientists believe this represents 1 percent of the total, so perhaps the Milky Way contains about 100 billion stars. [Large Numbers That Define the Universe]

Nobody knows how much the Milky Way weighs

milky way galaxy

(Image credit: Shutterstock)

On a related note, astronomers are still unsure exactly how much our galaxy weighs, with estimates ranging from 700 billion to 2 trillion times the mass of our sun. Getting a better grasp is no easy task. Most of the Milky Way’s mass — perhaps 85 percent — is in the form of dark matter, which gives off no light and so is impossible to directly observe, according to astronomer Ekta Patel of the University of Arizona in Tucson. Her recent study looked at how strongly our galaxy’s humongous mass gravitationally tugs on smaller galaxies orbiting it and updated the estimate of the Milky Way’s mass to 960 billion times the mass of the sun, Live Science previously reported.

The Milky Way is probably in a big, empty spot in the universe

milky way galaxy

(Image credit: Springel et al./Virgo Consortium)

Several studies have indicated that the Milky Way and its neighbors are living out in the boonies of the cosmos. From afar, the large-scale structure of the universe looks like a colossal cosmic web, with string-like filaments connecting dense regions separated by enormous, mostly empty voids. The emphasis in that last sentence should be on “mostly empty,” since our own galactic abode seems to be an inhabitant of the Keenan, Barger and Cowie (KBC) Void, named after three astronomers who identified it in a 2013 study in The Astrophysical Journal. Last year, a separate team looked at the motion of galaxies in the cosmic web to provide additional confirmation that we’re floating in one of the big, empty areas, Live Science previously reported.

Astronomers are trying to photograph the monster black hole at the Milky Way’s center

milky way galaxy

(Image credit: NASA/CXC/Columbia Univ./C. Hailey et al.)

Lurking in the heart of our galaxy is a hungry behemoth, a gigantic black hole with the weight of 4 million suns. Scientists know that it’s there because they can trace the paths of stars in the Milky Way’s center and see that they seem to orbit a supermassive object that can’t be seen. But in recent years, astronomers have been combining observations from multiple radio telescopes to try and get a glimpse of the environment surrounding the black hole, which is packed with gas and dust spinning around the black hole’s maw. The project, called the Event Horizon Telescope, expects to have preliminary images of the black hole’s edge in the coming months, according to the team’s blog. [Stephen Hawking’s Most Far-Out Ideas About Black Holes]

Small galaxies orbit the Milky Way and sometimes crash into it

milky way galaxy

(Image credit: Juan Carlos Muñoz/ESO)

When Portuguese explorer Ferdinand Magellan sailed through the Southern Hemisphere in the 16th century, he and his crew were among the first Europeans to report on circular clusters of stars in the night sky, according to the European Southern Observatory. These clusters are actually small galaxies that orbit our Milky Way like planets around a star, and they have been named the Small and Large Magellanic clouds. Many such dwarf galaxies orbit ours — and sometimes they get eaten by our massive Milky Way. Earlier this year, astronomers used new data from the Gaia satellite that showed millions of stars in our galaxy moving in similar narrow, “needle-like” orbits, suggesting they all originated from an earlier dwarf galaxy dubbed “the Gaia Sausage,” as Live Science reported at the time.

The Milky Way is full of toxic grease

milky way galaxy

(Image credit: NASA/JPL-Caltech)

Swirling through the mostly empty space between stars in our galaxy is a bunch of dirty grease. Oily organic molecules known as aliphatic carbon compounds are produced in certain types of stars and then are leaked out into interstellar space. A recent study found that these grease-like substances could account for between a quarter and one-half of the Milky Way’s interstellar carbon — five times more than previously believed, as Live Science reported in June. Though strange, the findings are cause for optimism, according to researchers. Because carbon is an essential building block of living things, finding it in abundance throughout the galaxy could suggest that other star systems harbor life.

The Milky Way is going to crash with its neighbor in 4 billion years

milky way galaxy

(Image credit: Shutterstock)

Sad to say, but our galaxy isn’t going to be here forever. Astronomers know that we are currently speeding toward our neighbor, the Andromeda galaxy, at around 250,000 mph (400,000 km/h). When the crash comes, in about 4 billion years, most research has suggested that the more massive Andromeda galaxy would swallow up our own and survive. But in a recent study, astronomers reweighed Andromeda and found that it was roughly equivalent to 800 billion suns, or about on par with the Milky Way’s mass, as Live Science previously reported. That means that exactly which galaxy will emerge less scathed from the future galactic crash remains an open question.

Stars from our galactic neighbors are racing toward the Milky Way

milky way galaxy

(Image credit: ESA/Marchetti et al 2018/NASA/ESA/Hubble/CC BY-SA 3.0 IGO)

Movie stars in films are known to swap spit, but who knew that galaxies in the universe sometimes swap stars? Researchers were recently searching for hypervelocity stars, which get thrown at mind-bending speeds from the Milky Way after interacting with the giant black hole in its center. What they found was even stranger — rather than flying away from our galaxy, most of the fast stars they spotted were barreling toward us. “These could be stars from another galaxy, zooming right through the Milky Way,” Tommaso Marchetti, an astronomer at Leiden University in the Netherlands, said in a statement. In the study, which was published Sept. 20 in the journal Monthly Notices of the Royal Astronomical Society, the authors suggest that these odd stars could have originated in the Large Magellanic Cloud or some other galaxy farther away and write in their paper that the discovered objects “may constitute the tip of the iceberg” of a large population of similar stars.

There are mysterious bubbles arising out of the Milky Way

milky way galaxy

(Image credit: NASA Goddard)

Imagine discovering that your living room, which you’ve seen a million times before, contained a previously unnoticed elephant. That’s more or less what happened to scientists in 2010 when they uncovered gigantic, never-before-seen structures stretching for 25,000 light-years above and below the galaxy. Named ‘Fermi bubbles’ after the telescope that found them, these gamma-ray-emitting objects have defied astronomers’ explanations ever since. Last year, a team gathered evidence suggesting that the bubbles are the aftermath of an energetic event 6 million to 9 million years ago, when the supermassive black hole in the galactic center swallowed a huge clump of gas and dust and burped out the giant, glowing clouds, according to NASA.

Our galaxy is being bombarded with bizarre energy pulses from the other side of the universe

milky way galaxy

(Image credit: OzGrav Swinburne University of Technology)

Over the last decade, astronomers keep detecting odd flashes of light coming at them from the distant cosmos. Known as fast radio bursts (FRBs), these mysterious signals have no agreed-upon explanation. Despite knowing about them for more than 10 years, researchers had until recently captured only 30 or so examples of these FRBs. But in a recent study, Australian scientists managed to find 20 more FRBs, nearly doubling the number of known objects, as Live Science previously reported. While they still don’t know the odd flashes’ origin, the team was able to determine that the light had traveled through several billion light-years of gas and dust, which imparted telltale signs on the signal, suggesting that the FRBs were coming from quite a long way off.

A Second Interstellar Visitor Has Arrived in Our Solar System. This Time, Astronomers Think They Know Where It Came From


Post 8795

A Second Interstellar Visitor Has Arrived in Our Solar System. This Time, Astronomers Think They Know Where It Came From

By Rafi Letzter – Staff Writer October 09, 2019

https://www.livescience.com/mysterious-comet-interstellar-krueger-borisov.html
When ‘Oumuamua passed through our solar system in 2017, no one could figure out where the object came from. But astronomers think they’ve worked out how Comet 2I/Borisov got here.

An artist's depiction of the first identified interstellar object, 'Oumuamua.

An artist’s depiction of the first identified interstellar object, ‘Oumuamua.
(Image: © M. Kornmesser/ESO)

For the second time ever, astronomers have detected an interstellar object plunging through our solar system. But this time, researchers think they know where it came from.
Gennady Borisov, an amateur astronomer working with his own telescope in Crimea, first spotted the interstellar comet on Aug. 30. His find made the object the first interstellar visitor discovered since oblong ‘Oumuamua flashed through our solar neighborhood back in 2017. Now, in a new paper, a team of Polish researchers has calculated the path this new comet — known as Comet 2I/Borisov or (in early descriptions) as C/2019 Q4 — took to arrive in our sun’s gravity well. And that path leads back to a binary red dwarf star system 13.15 light-years away, known as Kruger 60.
When you rewind Comet Borisov’s path through space, you’ll find that 1 million years ago, the object passed just 5.7 light-years from the center of Kruger 60, moving just 2.13 miles per second (3.43 kilometers per second), the researchers wrote.

That’s fast in human terms —— about the top speed of an X-43A Scramjet, one of the fastest aircraft ever built. But an X-43A Scramjet can’t overcome the sun’s gravity to escape our solar system. And the researchers found that if the comet were really moving that slowly at a distance of no more than 6 light-years from Kruger 60, it probably wasn’t just passing by. That’s probably the star system it came from, they said. At some point in the distant past, Comet Borisov lively orbited those stars the way comets in our system orbit ours.
Ye Quanzhi, an astronomer and comet expert at the University of Maryland who wasn’t involved in this paper, told Live Science that the evidence pinning Comet 2I/Borisov to Kruger 60 is pretty convincing based on the data available so far.
“If you have an interstellar comet and you want to know where it came from, then you want to check two things,” he said. “First, has this comet had a small pass distance from a planetary system? Because if it’s coming from there, then its trajectory must intersect with the location of that system.”
Though the 5.7 light-years between the new comet and Kruger may seem bigger than a “small gap” — nearly 357,000 times Earth’s distance from the sun — it’s close enough to count as “small” for these sorts of calculations, he said.
“Second,” Ye added, “usually comets are ejected from a planetary system due to gravitational interactions with major planets in that system.”
In our solar system, that might look like Jupiter snagging a comet that’s falling toward the sun, slingshotting it around in a brief, partial orbit and then flinging it away toward interstellar space.
“This ejection speed has a limit,” Ye said. “It can’t be infinite because planets have a certain mass,” and the mass of a planet determines how hard it can throw a comet into the void. “Jupiter is pretty massive,” he added, “but you can’t have a planet that’s 100 times more massive than Jupiter because then it would be a star.”
Related: 15 Amazing Images of Stars
That mass threshold sets an upper limit on the speeds of comets escaping star systems, Ye said. And the authors of this paper showed that Comet 2I/Borisov fell within the minimum speed and distance from Kruger 60 to suggest it originated there —assuming their calculations of its trajectory are correct.
Studying interstellar comets is exciting, Ye said, because it offers a rare opportunity to study distant solar systems using the precise tools scientists employ when examining our own. Astronomers can look at Comet 2I/Borisov using telescopes that might reveal details of the comet’s surface. They can figure out whether it behaves like comets in our own system (so far, it has) or does anything unusual, like ‘Oumuamua famously did. That’s a whole category of research that usually isn’t possible with distant solar systems, where small objects only ever appear —— if they’re visible at all —— as faint, discolored shadows on their suns.
This research, Ye said, means that anything we learn about Comet Borisov could be a lesson about Kruger 60, a nearby star system where no exoplanets have been discovered. ‘Oumuamua, by contrast, seems to have come from the general direction of the bright star Vega, but according to NASA’s Jet Propulsion Laboratory, researchers don’t believe that’s where the object originally came from, instead suggesting it likely came from a newly-forming star system (though researchers aren’t sure which one).. That would make Comet Borisov the first interstellar object ever traced to its home system, if these results are confirmed.
However, the paper’s authors were careful to point out that these results shouldn’t yet be considered conclusive. Astronomers are still collecting more data about Comet 2I/Borisov’s path through space, and additional data may reveal that the original trajectory was wrong and that the comet came from somewhere else.
The paper tracing the comet’s origin has not yet been published in a peer-reviewed journal, but it’s available on the preprint server arXiv.

In Images: Rising ‘Phoenix’ Aurora and Starburst Galaxies Light Up the Skies


Post 8794

In Images: Rising ‘Phoenix’ Aurora and Starburst Galaxies Light Up the Skies

https://www.livescience.com/65786-astronomy-photographer-of-the-year-photos.html
By Christine Lunsford June 25, 2019

Aurora Bird astronomy photographers

(Image credit: Copyright Alexander Stepanenko)

Russian photographer Alexander Stepanenko visited the Murmansk region in Russia for years, attempting to capture an image of the aurora over an abandoned military hydroelectric station. Stepanenko’s patience finally paid off on Sept. 10, 2018. This and other photos were recently selected for the shortlist of the Astronomy Photographer of the Year contest, organized by the Royal Observatory, Greenwich in the United Kingdom.

Read more about the “phoenix aurora” and other incredible astronomy photos.

Aurora outside the tiny cave

Aurora outside a tiny cave astronomy photographers

(Image credit: Copyright Sutie Yang)

In Seljalandsfoss, Iceland, on Jan. 8, 2019, Chinese photographer Sutie Yang caught a mesmerizing view of an aurora from inside a cavern, framing the aurora alongside Iceland’s Seljalandsfoss waterfall.

Deep in the heart of Mordor

Deep in the heart of Mordor astronomy photographers

(Image credit: Copyright Andrew Campbell)

Australian photographer Andrew Campbell captured NGC 7293 — the Helix Nebula — one of the brightest and closest examples of a gas cloud created at the end of the life of a sun-like star. The remnant of the star’s core is still so energetic that it causes the previously expelled gas to fluoresce in glowing rings. Campbell created this colorful composite image from an exposure lasting 63 hours and 58 minutes, taken in Melbourne, Australia on Nov. 27, 2018.

Devil’s Head Nebula

Depth and height of NGC 7822 astronomy photography

(Image credit: Copyright Laszlo Bagi)

For this image of the Devil’s Head Nebulae Complex, Hungarian photographer László Bagi used custom-built Newtonian reflecting telescope with an exposure of 29 hours, highlighting the nebula’s structure and depth. Bagi captured the photo in Szarvas, Hungary on Oct. 10, 2018.

Gum 12

Gum 12 astronomy photographers

(Image credit: Copyright Eddie Trimarchi)

The Gum Nebula, or Gum 12, is an emission nebula that extends 36 degrees across the night sky and is actually the very large remnant of the 12,000-year-old Vela supernova. The nebula mostly consists of hydrogen (red) and doubly ionized oxygen (blue). Australian photographer Eddie Trimarchi captured this bi-color image at Biggera Waters, Australia, on Feb. 25, 2018.

The Horsehead and Flame Nebula

The Horsehead and Flame Nebula astronomy photogrpahers

(Image credit: Copyright Conner Matherne)

American photographer Connor Matherne’s astonishing view of the Horsehead and Flame Nebulae was captured from the Deep Sky West Observatory in Rowe, New Mexico on Nov. 27, 2018. According to Matherne, his image was inspired by astrophotographer Ken Crawford’s image of the Horsehead Nebula, showcasing hydrogen filaments located within the blue nebula — NGC 2023 —, just below the Horsehead.

The Lord of the Rings and his court

The Lord of the Rings and his court astronomy photographers

(Image credit: Copyright Jordi Delpeix Borrell)

Spanish photographer Jordi Delpeix Borrell’s image features Saturn’s magnificent rings shining broad and bright alongside several of its bright satellites. Titan appears at the bottom right, Rhea is on the top left, Tethys and Dione are to the right of the planet, and Enceladus and Mimas are under the rings. Borrell photographed the planet and moons from Long Bay, Barbados on July 5, 2018.

Orion

orion astronomy photographers

(Image credit: Copyright Raul Villaverde Fraile)

Photographer Raul Villaverde Fraile of Spain captured one of the most photographed astronomical objects — the Orion Nebula — in an exposure lasting 33 hours and 45 minutes. The image was taken on Jan. 6, 2019, at Ocentejo, Castile-La Mancha, Spain.

Out on a Limb

Out on a Limb astronomy photographers

(Image credit: Copyright Alastair Woodward)

British photographer Alastair Woodward snapped this image of a solitary prominence on the limb of the solar disk from Derby, UK on July 8, 2019. The photographer inverted the image during processing to show both the prominence and details of the chromosphere — the second of three layers in the sun’s outer atmosphere. The image represents approximately 700 frames from a movie shot at 40 frames per second.

The Running Man Nebula

The Running Man Nebula astronomy photographers

(Image credit: Copyright Steven Mohr)

From Carapooee, Victoria, Australia, Australian photographer Steven Mohr snapped the Running Man Nebula on Jan. 15, 2019. The Running Man Nebula lies in the constellation of Orion, located some 1,500 light years from Earth.

The Sculptor Galaxy

The Sculptor Galaxy astronomy photographers

(Image credit: Copyright Bernard Miller/Martin Pugh)

Photographers Bernard Millar and Martin Pugh of the U.S. snapped the Sculptor Galaxy, also known as NGC 253, from Yass, New South Wales, Australia on Nov. 12, 2018. This is a starburst galaxy, which means it undergoes periods of intense star formation, and it is the largest galaxy in a cluster of galaxies called the Sculptor Group.

Seven-colour feather of the moon

Seven-colour feather of the moon astronomy photographers

(Image credit: Copyright Yiming Li)

Chinese photographer Yiming Li’s breathtaking image showcases the Moon’s elegant corona. Highlighted by clouds, this lunar view was captured in Dongguan, China on July 28, 2018.

A Titanium moon

Titanium moon astronomy photographers

(Image credit: Miguel Claro)

Photographer Miguel Claro of Portugal captured a stunning image of Earth’s moon from the Dark Sky Observatory in Alqueva, Portugal on Oct. 25, 2018.

Read more about the “phoenix aurora” and other incredible astronomy photos

 

 

Violent Solar Storms Are Happening Closer to Earth Than Anyone Thought Was Possible


Post 8793

Violent Solar Storms Are Happening Closer to Earth Than Anyone Thought Was Possible

https://www.livescience.com/magnetic-storm-originate-close-to-earth.html

By Yasemin Saplakoglu – Staff Writer a day ago
The spectacular solar storms that paint the polar skies in beautiful greens and pinks have a darker side.

This aurora was captured on camera from the International Space Station on June of 2017.

This aurora was captured on camera from the International Space Station in June 2017.
(Image: © NASA)

The spectacular solar storms that paint the polar skies in beautiful greens and pinks have a darker side: They have the power to wreak havoc on our electrical grid, communication systems and satellites. Now, a new study suggests that the source of these solar storms is much closer to our planet than previously thought.
Earth is shielded by a protective bubble known as the magnetosphere which blocks harmful solar radiation. But when the sun occasionally emits high-speed streams of radiation — and, with it, intense magnetic field lines — they can strongly interact with our planet’s own magnetic field.

As this solar wind hits the magnetosphere, the two sets of magnetic field lines become entangled. This interaction generates heat and accelerates the charged particles — ions and electrons— brought in by the solar wind, temporarily weakening the planet’s magnetic field and creating powerful magnetic storms that appear to us as auroras.

But because these storms are rare, and there aren’t enough satellites to observe them, it’s not clear exactly where and how this reconnection of magnetic field lines happened, the study’s researchers said in a statement.
To figure that out, the researchers used observations from NASA’s Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites. During solar storms, these satellites sit at Earth’s magnetotail — the part of the magnetosphere on the side of the planet not facing the sun — which becomes elongated by the solar wind. The researchers found that this magnetic reconnection — the event that sparks magnetic storms — can occur much closer to our planet than previously thought: about three to four Earth diameters away, according to the statement.

This artist's rendition shows what happens in Earth's magnetosphere during a magnetic storm. The three THEMIS satellites observed the reconnection of magnetic field lines close to the geosynchronous orbit. The reconnection site (X) created outflows of energized particles towards and away from the planet. The particles that went toward the planet carried energy along the magnetic field lines to power auroras at the planet's poles and were detected by the GOES weather satellite (left of the arrow).
This artist’s illustration shows what happens in Earth’s magnetosphere during a magnetic storm. The three THEMIS satellites observed the reconnection of magnetic field lines close to the geosynchronous orbit. The reconnection site (X) created outflows of energized particles towards and away from the planet. The particles that went toward the planet carried energy along the magnetic field lines to power auroras at the planet’s poles and were detected by the a weather satellite (left of the arrow). (Image credit: Emmanuel Masongsong/UCLA)

What’s more, a weather satellite in a near-Earth orbit (or geosynchronous orbit) detected energized electrons following the storm, suggesting that the reconnection event prompted ions and electrons to accelerate to high energies. The electrons that flow toward the planet carry energy along magnetic field lines to create the auroras we see.
This acceleration can be hazardous to the hundreds of satellites moving in geosynchronous orbit and also can be harmful to human DNA, thereby posing a risk to astronauts, according to the statement.
Moreover, solar storms can impact Earth-dwellers in significant ways. In 1921, for example, a magnetic storm disrupted telegraph communications and caused power outages that led to the burning of a train station in New York City, according to the statement.
“By studying the magnetosphere, we improve our chances of dealing with the greatest hazard to humanity venturing into space: storms powered by the sun,” lead author Vassilis Angelopoulos, a professor of space physics at UCLA, said in the statement. These findings might help astronauts and Earth-dwellers to better prepare for dangerous solar weather.
The findings were published Jan. 13 in the journal Nature Physics.