10 Astonishing Things You Should Know About the Milky Way

Anne Dirkse, Flickr // CC BY-SA 2.0
Anne Dirkse, Flickr // CC BY-SA 2.0

Our little star and the tiny planets that circle it are part of a galaxy called the Milky Way. Its name comes from the Greek galaxias kyklos ("milky circle") and Latin via lactea ("milky road"). Find a remote area in a national park, miles from the nearest street light, and you'll see exactly why the name makes sense and what all the fuss is about. Above is not a sky of black, but a luminous sea of whites, blues, greens, and tans. Here are a few things you might not know about our spiraling home in the universe.

1. THE MILKY WAY IS GIGANTIC.

The Milky Way galaxy is about 1,000,000,000,000,000,000 kilometers (about 621,371,000,000,000,000 miles) across. Even traveling at the speed of light, it would still take you well over 100,000 years to go from one end of the galaxy to the other. So it's big. Not quite as big as space itself, which is "vastly, hugely, mind-bogglingly big," as Douglas Adams wrote, but respectably large. And that's just one galaxy. Consider how many galaxies there are in the universe: One recent estimate says 2 trillion.

2. IT'S JAM-PACKED WITH CELESTIAL STUFF.

artist's illustration of the milky way galaxy and its center
An artist's concept of the Milky Way and the supermassive black hole Sagittarius A* at its core.
ESA–C. Carreau

The Milky Way is a barred spiral galaxy composed of an estimated 300 billion stars, along with dust, gas, and celestial phenomena such as nebulae, all of which orbits around a hub of sorts called the Galactic Center, with a supermassive black hole called Sagittarius A* (pronounced "A-star") at its core. The bar refers to the characteristic arrangement of stars at the interior of the galaxy, with interstellar gas essentially being channeled inward to feed an interstellar nursery. There are four spiral arms of the galaxy, with the Sun residing on the inner part of a minor arm called Orion. We're located in the boondocks of the Milky Way, but that is OK. There is definitely life here, but everywhere else is a question mark. For all we know, this might be the galactic Paris.

3. FOR A SPIRAL GALAXY, IT'S PRETTY TYPICAL …

If you looked at all the spiral galaxies in the local volume of the universe, the Milky Way wouldn't stand out as being much different than any other. "As galaxies go, the Milky Way is pretty ordinary for its type," Steve Majewski, a professor of astronomy at the University of Virginia and the principal investigator on the Apache Point Observatory Galactic Evolution Experiment (APOGEE), tells Mental Floss. "It's got a pretty regular form. It's got its usual complement of star clusters around it. It's got a supermassive black hole in the center, which most galaxies seem to indicate they have. From that point of view, the Milky Way is a pretty run-of-the-mill spiral galaxy."

4. …AND YET IT STANDS OUT AMONG ALL GALAXIES.

On the other hand, he tells Mental Floss, spiral galaxies in general tend to be larger than most other types of galaxies. "If you did a census of all the galaxies in the universe, the Milky Way would seem rather unusual because it is very big, our type being one of the biggest kinds of galaxies that there are in the universe." From a human perspective, the most important thing about the Milky Way is that it definitely managed to produce life. If they exist, the creatures in Andromeda, the galaxy next door (see #9), probably feel the same way about their own.

5. FIGURING OUT ITS STRUCTURE FROM THE INSIDE IS A CHALLENGE.


John McSporran, Flickr // CC BY 2.0

We have a very close-up view of the phenomena and forces at work in the Milky Way because we live inside of it, but that internal perspective places astronomers at a disadvantage when it comes to determining a galactic pattern. "We have a nice view of the Andromeda galaxy because we can see the whole thing laid out in front of us," Majewski says. "We don't have that opportunity in the Milky Way."

To figure out its structure, astronomers have to think like band members during a football halftime show. Though spectators in the stands can easily see the letters and shapes being made on the field by the marchers, the band can't see the shapes they are making. Rather, they can only work together in some coordinated way, moving to make these patterns and motions on the field. So it is with telescopes and stars.

6. INTERSTELLAR DUST BLOCKS OUR VIEW OF SOME PARTS OF THE GALAXY.

Interstellar dust further stymies astronomers. "That dust blocks our light, our view of the more distant parts of the Milky Way," Majewski says. "There are areas of the galaxy that are relatively obscured from view because they are behind huge columns of dust that we can't see through in the optical wavelengths that our eyes work in." To ameliorate this problem, astronomers sometimes work in longer wavelengths such as radio or infrared, which lessen the effects of the dust.

7. THE MILKY WAY SPINS, BUT ITS SPEED DOESN'T ADD UP …

Astronomers can make pretty reasonable estimates of the mass of the galaxy by the amount of light they can see. They can count the galaxy's stars and calculate how much those stars should weigh. They can account for all the dust in the galaxy and all of the gas. And when they tally the mass of everything they can see, they find that it is far short of what is needed to account for the gravity that causes the Milky Way to spin.

In short, our Sun is about two-thirds of the way from the center of the galaxy, and astronomers know that it goes around the galaxy at about 144 miles per second. "If you calculate it based on the amount of matter interior to the orbit of the Sun, how fast we should be going around, the number you should get is around 150 or 160 kilometers [93–99 miles] per second," Majewski says. "Further out, the stars are rotating even faster than they should if you just account for what we call luminous matter. Clearly there is some other substance in the Milky Way exerting a gravitational effect. We call it dark matter."

8. … AND WE BLAME DARK MATTER FOR THAT.

Dark matter is a big problem in galactic studies. "In the Milky Way, we study it by looking at the orbits of stars and star clusters and satellite galaxies, and then trying to figure out how much mass do we need interior to the orbit of that thing to get it moving at the speed that we can measure," Majewski says. "And so by doing this kind of analysis for objects at different radii across the galaxy, we actually have a fairly good idea of the distribution of the dark matter in the Milky Way—and yet we still have no idea what the dark matter is."

9. THE MILKY WAY IS ON A COLLISION COURSE WITH ANDROMEDA. BUT DON'T PANIC.

andromeda galaxy
The Andromeda galaxy
ESA/Hubble & NASA

Sometime in the next 4 or 5 billion years, the Milky Way and Andromeda galaxies will smash into each other. The two galaxies are about the same size and have about the same number of stars, but there is no cause for alarm. "Even though there are 300 billion stars in our galaxy and a comparable number, or maybe more, in Andromeda, when they collide together, not a single star is expected to hit another star. The space between stars is that vast," Majewski says.

10. WE'RE THROWING EVERYTHING WE HAVE AT STUDYING IT.

There are countless spacecraft and telescopes studying the Milky Way. Most famous is the Hubble Space Telescope, while other space telescopes such as Chandra, Spitzer, and Kepler are also returning data to help astronomers unlock the mysteries of our swirling patch of stars. The next landmark telescope in development is NASA's James Webb Space Telescope. It should finally launch in 2019. Meanwhile, such ambitious projects as APOGEE are working out the structure and evolution of our spiral home by doing "galactic archaeology." APOGEE is a survey of the Milky Way using spectroscopy, measuring the chemical compositions of hundreds of thousands of stars across the galaxy in great detail. The properties of stars around us are fossil evidence of their formation, which, when combined with their ages, helps astronomers understand the timeline and evolution of the galaxy we call home. 

The 10 Best Memorial Day 2020 Sales

iRobot,GoWise,Funko via Wayfair, Entertainment Earth
iRobot,GoWise,Funko via Wayfair, Entertainment Earth

The Memorial Day sales have started early this year, and it's easy to find yourself drowning in offers for cheap mattresses, appliances, shoes, and grills. To help you cut through the noise and focus on the best deals around, we threw together some of our favorite Memorial Day sales going on right now. Take a look below.

1. Leesa

A Leesa Hybrid mattress.
A Leesa Hybrid mattress.
Leesa

Through May 31, you can save up to $400 on every mattress model Leesa has to offer, from the value-minded Studio by Leesa design to the premium Leesa Legend, which touts a combination of memory foam and micro-coil springs to keep you comfortable in any position you sleep in.

Find it: Leesa

2. Sur La Table

This one is labeled as simply a “summer sale,” but the deals are good only through Memorial Day, so you should get to it quickly. This sale takes up to 20 percent off outdoor grilling and dining essentials, like cast-iron shrimp pans ($32), a stainless steel burger-grilling basket ($16), and, of course, your choice of barbeque sauce to go along with it.

Find it: Sur la Table

3. Wayfair

KitchenAid Stand Mixer on Sale on Wayfair.
Wayfair/KitchenAid

Wayfair is cutting prices on all manner of appliances until May 28. Though you can pretty much find any home appliance imaginable at a low price, the sale is highlighted by $130 off a KitchenAid stand mixer and 62 percent off this eight-in-one GoWise air fryer.

And that’s only part of the brand’s multiple Memorial Day sales, which you can browse here. They’re also taking up to 40 percent off Samsung refrigerators and washing machines, up to 65 percent off living room furniture, and up to 60 percent off mattresses.

Find it: Wayfair

4. Blue Apron

If you sign up for a Blue Apron subscription before May 26, you’ll save $20 on each of your first three box deliveries, totaling $60 in savings. 

Find it: Blue Apron

5. The PBS Store

Score 20 percent off sitewide at Shop.PBS.org when you use the promo code TAKE20. This slashes prices on everything from documentaries like Ken Burns’s The Roosevelt: An Intimate History ($48) and The Civil War ($64) to a Pride & Prejudice tote bag ($27) and this precious heat-changing King Henry VIII mug ($11) that reveals the fates of his many wives when you pour your morning coffee.

Find it: The PBS Store

6. Amazon

eufy robot vacuum.
Amazon/eufy

While Amazon doesn’t have an official Memorial Day sale, the ecommerce giant still has plenty of ever-changing deals to pick from. Right now, you can take $100 off this outdoor grill from Weber, $70 off a eufy robot vacuum, and 22 percent off the ASUS gaming laptop. For more deals, just go to Amazon and have a look around.

7. Backcountry

You can save up to 50 percent on tents, hiking packs, outdoor wear, and more from brands like Patagonia, Marmot, and others during Backcountry's Memorial Day sale.

Find it: Backcountry

8. Entertainment Earth

Funko Pops on Sale on Entertainment Earth.
Entertainment Earth/Funko

From now until June 2, Entertainment Earth is having a buy one, get one half off sale on select Funko Pops. This includes stalwarts like the Star Wars and Batman lines, and more recent additions like the Schitt's Creek Funkos and the pre-orders for the upcoming X-Men movie line.

Find it: Entertainment Earth

9. Moosejaw

With the promo code SUNSCREEN, you can take 20 percent off one full-price item at Moosejaw, along with finding up to 30 percent off select items during the outdoor brand's summer sale. These deals include casual clothing, outdoor wear, trail sneakers, and more. 

Find it: Moosejaw

10. Osprey

Through May 25, you can save 25 percent on select summer items, and 40 percent off products from last season. This can include anything from hiking packs and luggage to outdoorsy socks and hats. So if you're planning on getting acquainted with the great outdoors this summer, now you can do it on the cheap.

Find it: Osprey

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

NASA's Juno Probe Captures Stunning New Look at Jupiter's Swirling Atmosphere

NASA/JPL-Caltech/SwRI/MSSS
NASA/JPL-Caltech/SwRI/MSSS

Upon entering Jupiter's orbit in 2016, NASA's Juno spacecraft provided us with an intimate look at the largest planet in our solar system. Four years later, the probe continues to shed light on the gas giant. Two new pictures taken by the JunoCam show Jupiter's swirling, iridescent atmosphere in striking detail, and they're raising new questions about the planet's composition, Space.com reports.

The first image, captured on February 17, 2020, shows bands of haze particles extending above the main level of Jupiter's eddying clouds. NASA scientists aren't sure what these bands might be, but one theory is that they're the byproduct of the jet stream bands that have been known to form around the same spot.

Close-up of Jupiter's atmosphere.
A close-up of Jupiter's atmosphere.
NASA/JPL/SwRI/MSSS; image processing by Gerald Eichstädt

In the second picture, taken on April 10, Jupiter's upper atmosphere is shown in even clearer definition. Different types of clouds can be picked out of the abstract scene; the smaller, brighter clouds that appear to rise up from the edges of the swirling patterns are called "pop-up" clouds.

Close-up of Jupiter's atmosphere.
A tapestry of various types of clouds.
NASA/JPL-Caltech/SwRI/MSSS

Juno has performed more than 25 close fly-bys of Jupiter. Thanks to the data the spacecraft has gathered, we now know the planet's poles are covered by Texas-sized ammonia cyclones, and that its interior is much different from what was previously believed.

[h/t Space.com]