NASA, ESA, and A. Simon (NASA Goddard)
NASA, ESA, and A. Simon (NASA Goddard)

Look Up! Jupiter Is Close, Bright, and Showing Its Stripes

NASA, ESA, and A. Simon (NASA Goddard)
NASA, ESA, and A. Simon (NASA Goddard)

Look up tonight and you’ll see a big, bright, beautiful spot of light that looks like it would be perfect for taking you to Neverland. DO NOT FOLLOW IT. It is not the “second star to the right.” It’s not even a star. Follow it and you will be killed by a massive radiation belt that surrounds it. Reach it and you will be ripped apart by its intense gravity. And if your spaceship survives all of that (it won’t), you will be obliterated when you reach its liquid metallic hydrogen core. What you are seeing tonight is the planet Jupiter, and tonight it is as close to the Earth as it’s going to get this year. So what is going on up there?

Tonight Jupiter is on the opposite side of the Earth as the Sun, or “at opposition.” Because these objects are in a line—Sun, Earth, Jupiter—the disc we see is fully lit by direct sunlight. Conversely, were you to stand on the surface of Jupiter (you can’t because it doesn’t have one), Earth would seem totally black. You might be wondering whether the Earth’s shadow will cause a Jovian eclipse, and the answer is no. Tiny Earth’s shadow could no more blot out Jupiter than a fly could block the bat signal. During opposition this year, Jupiter will be a mere 414 million miles away from us. Everyone be on your best behavior.

If you have a telescope, tonight you are in for a treat. If the light pollution in your area is at a minimum, your skies are clear, and if you give your eyes a good 45 minutes or so to adjust to the darkness, when you point your glass at Jupiter and focus, you’re going to see some magical things. First: its beautiful, swirling, colorful bands of clouds. Jupiter is all clouds all the time, and not like Venus—a smudge of basically the same color from pole to pole. Rather, Jupiter is characterized by stark and contrasting parallel bands of clouds. Brown stripes and white stripes and rust stripes and tan stripes. They’re easy, relatively speaking, to discern with a telescope.

To be clear: What you will see from your backyard is not going to look like it was taken by Hubble, as the gorgeous portrait above was just a few days ago. When you look through the eyepiece, Jupiter isn’t suddenly going to look like the Moon. You’re going to have to work at this and really set yourself to the task of seeing the details. But once you succeed, you’ll know it immediately.

After you’ve experienced the wonder of our place in the cosmos, it’s time to move on to step 2: the Galilean moons, named for the guy who discovered them. Though Jupiter has about 67 known moons, most of them are very small. When Galileo set his telescope to the study of Jupiter in 1610, he noticed three “fixed stars” in a line through that planet. He later noticed that one of them vanished, and later reappeared. He then found a fourth. What he realized he was seeing were moons orbiting a planet, which annihilated the notion that all bodies in space must orbit the Earth. (This did not go over well with the Church, either, though in truth Galileo was obnoxious about the whole thing, and his later house arrest had as much to do with that as anything else.) The moons he saw were Io, Ganymede, Europa, and Callisto.

You should be able to see the moons even with a powerful set of binoculars; look for pinpricks in a line through Jupiter, just as Galileo saw. Once you check that box, it’s on to the next challenge: finding the famous Giant Red Spot. You’ll need a more powerful telescope for this, but the secret to finding the Giant Red Spot on Jupiter is to look closely at Jupiter for a giant red spot. How giant is it? Twice-as-large-as-the-Earth giant.

The Eeyore in you is probably wondering what you can do if it rains tonight, or if clouds roll in and settle for a spell. Good news! Starting at 4:30 EDT, Slooh will have a Jupiter livestream, during which astronomers will explain what’s going on up there. The livestream will also feature views from remote telescopes, giving you some pretty wondrous images without the trouble of being in nature or forcing your poor, weary pupils to expand and adjust to the unpleasantness of darkness. If all that is still too much for you, here are the images of Jupiter taken by the Galileo spacecraft. You could also watch this short NASA video about all the footage Hubble has captured over the years of Jupiter and its moons.

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


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.


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.


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."


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.


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.


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.


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."


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."


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.


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. 

Mysterious 'Hypatia Stone' Is Like Nothing Else in Our Solar System

In 1996, Egyptian geologist Aly Barakat discovered a tiny, one-ounce stone in the eastern Sahara. Ever since, scientists have been trying to figure out where exactly the mysterious pebble originated. As Popular Mechanics reports, it probably wasn't anywhere near Earth. A new study in Geochimica et Cosmochimica Acta finds that the micro-compounds in the rock don't match anything we've ever found in our solar system.

Scientists have known for several years that the fragment, known as the Hypatia stone, was extraterrestrial in origin. But this new study finds that it's even weirder than we thought. Led by University of Johannesburg geologists, the research team performed mineral analyses on the microdiamond-studded rock that showed that it is made of matter that predates the existence of our Sun or any of the planets in the solar system. And, its chemical composition doesn't resemble anything we've found on Earth or in comets or meteorites we have studied.

Lead researcher Jan Kramers told Popular Mechanics that the rock was likely created in the early solar nebula, a giant cloud of homogenous interstellar dust from which the Sun and its planets formed. While some of the basic materials in the pebble are found on Earth—carbon, aluminum, iron, silicon—they exist in wildly different ratios than materials we've seen before. Researchers believe the rock's microscopic diamonds were created by the shock of the impact with Earth's atmosphere or crust.

"When Hypatia was first found to be extraterrestrial, it was a sensation, but these latest results are opening up even bigger questions about its origins," as study co-author Marco Andreoli said in a press release.

The study suggests the early solar nebula may not have been as homogenous as we thought. "If Hypatia itself is not presolar, [some of its chemical] features indicate that the solar nebula wasn't the same kind of dust everywhere—which starts tugging at the generally accepted view of the formation of our solar system," Kramer said.

The researchers plan to further probe the rock's origins, hopefully solving some of the puzzles this study has presented.

[h/t Popular Mechanics]


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