This Is What Lunar Eclipses Can Teach Us About The Universe
“By looking at the sky alone, we can see the apparent, angular sizes of the Sun and Moon.
But when the Sun, Earth, and Moon all align to produce a total eclipse, it teach us how far astronomical distances truly are.
During a lunar eclipse, the Earth’s shadow falls on the Moon…”
If you wanted to learn the distances to the stars, you have to start closer: with distances and length scales you can measure before reaching for the heavens. During a total lunar eclipse, we can get there! We can not only determine the shape of the Earth, but also the Earth-Moon distance and the size of the Moon. With a little bit of care in our measurements, we can know the Earth-Sun distance and the size of the Sun, too, and this gives us a calibration point to reach for the stars. Simply by looking at relative brightness or, for more accurate results, a parallax measurement, we can learn the distance to astronomical objects beyond our Solar System.
All from measurements you can make during an eclipse, with no special equipment like a laser reflector on the Moon. Come get the scoop today!
Fading total lunar eclipse, Munich, 28.7.18
Our Local Group Is Being Eaten, And We Just Found The Galactic Leftovers
“Two of the Milky Way’s larger satellites — the Magellanic Clouds — are interacting, forming stars, and on track to be devoured. But one of Andromeda’s satellites is even more interesting. M32 is the smallest galaxy in the Messier catalog: just 6,500 light years across, with ~3 billion solar masses of material. Its dense core houses a multi-million solar mass black hole, extremely unusual for a small galaxy. It suggests that M32 was once much larger, and has been partially cannibalized.”
Here in the local group, we have Andromeda, the Milky Way, and about 60 galaxies that are much smaller. Four of the top 10 galaxies are actually satellites of either the Milky Way or Andromeda. The Large and Small Magellanic Clouds are less than 200,000 light years from the Milky Way, with M32 and M110 in tight orbit around Andromeda. But M32 is no ordinary satellite! In a brand new study published today in Nature Astronomy, scientists took several pieces of evidence and combined them, concluding that M32 is actually a remnant of the third largest galaxy in the Local Group: M32p, which was mostly devoured 2 billion years ago by Andromeda.
In the Universe, all we have left are the survivors, but thanks to some fascinating galactic archaeology, we can reconstruct exactly where it all came from!
The Brightest Galaxy In The Universe Is Surprisingly Young And Tiny
“In 2015, a new record was set for the brightest known galaxy, thanks to observations with the WISE telescope. Supermassive black holes power Extremely Luminous Infrared Galaxies. The brightest ones shine 10,000+ times as bright as our Milky Way.Although the Universe is just 10% of its current age and the galaxy is even smaller than ours, it outshines them all.”
I want you to close your eyes and imagine the Milky Way: a typical galaxy. Now, imagine a different galaxy, the brightest one you can think up. What does it look like? How do you imagine it?
Do you imagine something large, massive, with hundreds or even thousands of times as many stars? Do you imagine something that’s built itself up over billions of years? Well if that’s what you imagined, prepare to be shocked! The brightest ones of all are young, ultra-distant, and even smaller than our own galaxy!
Here’s the brightest galaxy in the Universe, which is turbulent, dusty, and looks nothing like you might expect!
Meet The Universe’s First-Ever Supermassive Binary Black Holes
“In 1891, the object OJ 287, 3.5 billion light years distant and a blazar itself, optically bursted. Every 11-12 years since, it’s produced another burst, recently discovered to have two, narrowly-separated peaks. Its central, supermassive black hole is 18 billion solar masses, one of the largest known in the Universe. This periodic double-burst arises from a 100-150 million solar mass black hole punching through the primary’s accretion disk.”
The big problem with black holes is that, well, they’re so dark. They don’t emit any detectable light of their own, so we have to rely on indirect, secondary signals to infer their existence. That usually arises in the form of radio and X-ray radiation from matter that gets accelerated by the black hole’s extreme gravity, as well as from the magnetic fields that an accretion disk around the black hole can create. The radiation can form jets, and when a jet points at our eyes, we see a blazar. Well, the system OJ 287 has a periodic blazar that flares in a double-burst every 11-12 years, indicative of a large, supermassive black hole orbiting an even more massive behemoth, punching through the accretion disk twice with every orbit.
Come meet OJ 287, first found to burst way back in 1891, and still one of only two supermassive black hole binaries known in the Universe!
Remnants Of Our Solar System’s Formation Found In Our Interplanetary Dust
“Our naive picture of a disk that gets very hot, fragments, and cools to then form planets may be hopelessly oversimplified. Instead, we’ve learned that it may actually be cold, outer material that holds the key to our planetary backyard. If the conclusions of the Ishii et al. paper stand the test of time, we may have just revolutionized our understanding of how all planetary systems come into being.”
How did Earth (and the other planets) form? According to conventional wisdom, a molecular cloud collapsed, formed a protoplanetary disk, funneled material into the center, and gave birth to a star. This star then blew off the gas and light elements from the inner Solar System, with the planets we have today representing the survivors from these hot, early stages. Only, what if that picture weren’t correct after all? What if the material that gave rise to our (and other) worlds wasn’t forged in an inferno, but in a colder, more distant environment that only fell into the inner reaches at a later time?
The way to decide would be to identify and examine material left over from these early stages of Solar System formation in enough detail. For the first time, we’ve done exactly that. Don’t miss the results!
New Stars Turn Galaxies Pink, Even Though There Are No ‘Pink Stars’
“New star-forming regions produce lots of ultraviolet light, which ionizes atoms by kicking electrons off of their nuclei.
These electrons then find other nuclei, creating neutral atoms again, eventually cascading down through its energy levels.
Hydrogen is the most common element in the Universe, and the strongest visible light-emitting transition is at 656.3 nanometers.
The combination of this red emission line — known as the Balmer alpha (or Hα) line — with white starlight adds up to pink.”
When you look through a telescope’s eyepiece at a distant galaxy, it will always appear white to you. That’s because, on average, starlight is white, and your eyes are more sensitive to white light than any color in particular. But with the advent of a CCD camera, collecting individual photons one-at-a-time, you can more accurately gauge an astronomical object’s natural color. Even though new stars are predominantly blue in color, star-forming regions and galaxies appear pink. The problem compounds itself when you realize there isn’t any such thing as a pink star! And yet, there’s a straightforward physical explanation for what we see.
It’s a combination of ultraviolet radiation, white starlight, and the physics of hydrogen atoms that turn galaxies pink. Find out how, with some incredible visuals, today!
The 5 Most Important Rules For Scientists Who Write About Science
“Remember that your number one goal, if you’re a scientist writing about your science, is to increase the excitement and knowledge of your audience about what it is that you do. What we’re learning about all aspects of the Universe is expanding and increasing every day, and that joy and wonder should carry over to all of us in our daily lives. We cannot be experts in each and every field, but that underscores exactly why we need experts, and to respect true expertise when we encounter it.
If we take care to communicate responsibly, we can all gain a greater awareness of what it is that we do understand, as well as an appreciation for what that knowledge means. We may never run out of questions to ponder about the Universe itself, but with a little care and effort, we can all come a little bit closer to comprehending the answers.”
For most of us, we recognize that our expertise is extremely limited in all but a few areas. In order to learn what’s going on at the cutting edge of human knowledge, we have to go to the experts. In fields like physics, astronomy, biology, and chemistry, that means going to the scientists who study those fields. Yet scientists who communicate their own science often are some of the worst communicators out there, either getting mired in the details and losing the big picture or oversimplifying things to the point where they misinform their audience. Yet, if they just followed these five rules, they could avoid the most common mistakes and do what they set out to: inform the world about what they do and why it matters.
Come get the five most important rules for scientists who write about science. I bet you find value here even if you’re not a scientist yourself!
Is Humanity Ignoring Our First Chance For A Mission To An Oort Cloud Object?
“In 2003, scientists discovered an object beyond Neptune that was unlike any other: Sedna. While there were larger dwarf planets beyond Neptune, and comets that would travel farther from the Sun, Sedna was unique for how far it always remained from the Sun. It always remained more than twice as distant from the Sun as Neptune was, and would achieve a maximum distance nearly 1,000 times as far as the Earth-Sun distance. And despite all that, it’s extremely large: perhaps 1,000 kilometers in diameter. It’s the first object we’ve ever found that might have originated from the Oort cloud. And we’ll only get two chances if we want to send a mission there: in 2033 and 2046. Right now, there isn’t even a proposed NASA mission looking at the possibility. If we do nothing, the opportunity will simply pass us by.”
Out beyond the eight planets of our Solar System, a large number of regions, all containing frozen objects, are theorized to exist. Innermost is the Kuiper belt, consisting of a wide variety of bodies, but all of which come quite close to Neptune’s orbit and feel its gravitational influence. Beyond that are the scattered disk objects: objects kicked by one of the gas giants out to greater distances. Beyond that are the detached objects, which have undergone multiple gravitational interactions and no longer come close to Neptune. And finally, there are the sednoids: objects that never come within double the Sun-Neptune distance of the Sun. There are only two known, and the first one, Sedna, is so large that it’s surely a dwarf planet. With an aphelion of approximately 1000 A.U., it may well have an origin in the inner Oort cloud, which is hitherto only theorized.
Fantastically, we have two launch windows for a mission to Sedna, if we were interested in going. Why are we not clamoring for this mission, and for the potential chance to explore the Oort cloud for the first time?!
Hubble Catches New Stars, Individually, Forming In Galaxies Beyond The Milky Way
“There are a massive variety of star-forming regions nearby, and Hubble’s new Legacy ExtraGalactic UV Survey (LEGUS) is now the sharpest, most comprehensive one ever.
By imaging 50 nearby, star-forming spiral and dwarf galaxies, astronomers can see how the galactic environment affects star-formation.”
Within galaxies, new stars are going to be formed from the existing population of gas. But how that gas collapses and forms stars, as well as the types, numbers, and locations of the stars that will arise, is highly dependent on the galactic environment into which they are born. Dwarf galaxies, for example, tend to form stars when a nearby gravitational interaction triggers them. These bursts occur periodically, leading to multiple populations of stars of different ages. Spirals, on the other hand, form their new stars mostly along the lines traced by their arms, where the dust and gas is densest. Thanks to the Hubble Space Telescope, we’re capable of finding these stars and resolving them individually, using a combination of optical and ultraviolet data.
The best part? These are individually resolved stars from well outside our own galaxy: in 50 independent ones. Here’s what Hubble’s new LEGUS survey is revealing.