How Do Cats Deal With Being Weightless?

Screenshot from the "I Can Has Gravity" video.

Since my previous post was about dogs, its time to give equal time to the cats … although I’m guessing the cat lovers of the world won’t have a great reaction to this one. Here’s some footage from some the Aerospace Medical Research Laboratories which include a test of the effects of weightlessness on cats in a C-131 “vomit comet” that simulates weightlessness. Best I can tell, this research was done in 1947. Think of it in the same vein as all those weird tests the early astronauts had to endure.

The text from the video: “In these experiments you can see the disorientation resulting when an animal is suddenly placed in a weightless state. Cats when dropped under normal conditions will invariably rotate their bodies longitudinally in midar and land on their feet. This automatic reflex action is almost completely lost under weightlessness.”

The research was conducted by Bioastronautics Research, part of the Air Force and the Department of Defense.

Amy Shira Teitel has a great post about the early medical tests on astronauts: As she wrote, “The Mercury astronauts only half joked during a 1959 press conference that the doctors had probed every orifice the human male has to offer, and then some, all in the name of ‘science’.”

Is Everything Actually Shrinking?

Is Everything Actually Shrinking?

Whoa, here’s something to think about. Maybe the Universe isn’t expanding at all. Maybe everything is actually just shrinking, so it looks like it’s expanding. Turns out, scientists have thought of this.

Videos Suggested for You:

132 - What Came Before The Big Bang_ 136 - Why Is Space Black_

Video Transcript

It’s tinfoil hat day again at The Guide To Space. There’s some people who would have you believe the Universe is expanding. They’re peddling this idea it all started with a bang, and that expansion is continuing and accelerating. Yet, they can’t tell us what force is causing this acceleration. Just “dark energy”, or some other JK Rowling-esque sounding thing. Otherwise known as the acceleration that shall not be named, and it shall be taught in the class which follows potions in 3rd period.

I propose to you, faithful viewer, an alternative to this expansionist conspiracy. What if distances are staying the same, and everything is in fact, shrinking? Are we destined to compress all the way down to the Microverse? Is it only a matter of time before our galaxy starts drinking its coffee from a thimble or perhaps sealed in a pendant hanging on Orion’s belt? So, could we tell if that’s actually what’s going on?

Representation of the timeline of the universe over 13.7 billion years, and the expansion in the universe that followed. Credit: NASA/WMAP Science Team.
Representation of the timeline of the universe over 13.7 billion years, and the expansion in the universe that followed. Credit: NASA/WMAP Science Team.

Better get some scotch tape for the hats, kids. This one gets pretty rocky right out of the gate.
The first horrible and critical assumption here is that shrinking objects and an expanding universe would look exactly the same, which without magic or handwaving just isn’t the case. But you don’t have to take my word for it, we have science to punch holes in our Shrink-truther conspiracy.

Let’s start with distances. If we assumed the Earth and everything on it was getting smaller, we’d also be shrinking things like meter sticks. In the past they would have been larger. If everything was larger in the past, including the length of a meter, this means the speed of light would have appeared slower in the past. So was the speed of light slower in the past? I’m afraid it wasn’t, which really hobbles the shrinky-dink universe plot. But how do we know that?

The diagram shows the electromagnetic spectrum, the absorption of light by the Earth's atmosphere and illustrates the astronomical assets that focus on specific wavelengths of light. ALMA at the Chilean site and with modern solid state electronics is able to overcome the limitations placed by the Earth's atmosphere. (Credit: Wikimedia, T.Reyes)
The diagram shows the electromagnetic spectrum, the absorption of light by the Earth’s atmosphere and illustrates the astronomical assets that focus on specific wavelengths of light. ALMA at the Chilean site and with modern solid state electronics is able to overcome the limitations placed by the Earth’s atmosphere. (Credit: Wikimedia, T.Reyes)

You’ve probably seen spectral lines before or at least heard them referenced. Scientists use them to determine the chemical composition of materials. A changing speed of light would affect the spectral lines of distant objects, and because some people are just super smart and were able to do the math on this, we know that when we look at distant gas clouds we find the speed of light has changed no more than one part in a billion over the past 7 billion years.

Shrinking objects would also become more dense over time. This means that the universal constant of gravity should appear smaller in the past. Some have actually studied this, to determine whether it has changed over time, and they’ve also seen no change.

Artists illustration of the expansion of the Universe (Credit: NASA, Goddard Space Flight Center)
Artists illustration of the expansion of the Universe (Credit: NASA, Goddard Space Flight Center)

If objects in the Universe were shrinking, the Universe would actually be collapsing. If galaxies weren’t moving away from each other, their gravity would cause them to start falling toward each other. If they were shrinking, assuming their mass doesn’t change, their gravity would be just as strong, so shrinking wouldn’t stop their mutual attraction. A Universe of shrinking objects would look exactly opposite to what we observe.

So, good news. We’re pretty sure that objects, and us, and all other things in the Universe are not shrinking. We’re still not sure why anyone would name a thing Shrinky Dinks. Especially a craft toy marketed at children.

A Universe of 10 Dimensions

Superstrings may exist in 11 dimensions at once. Via National Institute of Technology Tiruchirappalli.

When someone mentions “different dimensions,” we tend to think of things like parallel universes – alternate realities that exist parallel to our own but where things work differently. However, the reality of dimensions and how they play a role in the ordering of our Universe is really quite different from this popular characterization.

To break it down, dimensions are simply the different facets of what we perceive to be reality. We are immediately aware of the three dimensions that surround us – those that define the length, width, and depth of all objects in our universes (the x, y, and z axes, respectively).

Beyond these three visible dimensions, scientists believe that there may be many more. In fact, the theoretical framework of Superstring Theory posits that the Universe exists in ten different dimensions. These different aspects govern the Universe, the fundamental forces of nature, and all the elementary particles contained within.

The first dimension, as already noted, is that which gives it length (aka. the x-axis). A good description of a one-dimensional object is a straight line, which exists only in terms of length and has no other discernible qualities. Add to that a second dimension, the y-axis (or height), and you get an object that becomes a 2-dimensional shape (like a square).

The third dimension involves depth (the z-axis) and gives all objects a sense of area and a cross-section. The perfect example of this is a cube, which exists in three dimensions and has a length, width, depth, and hence volume. Beyond these three dimensions reside the seven that are not immediately apparent to us but can still be perceived as having a direct effect on the Universe and reality as we know it.

The timeline of the universe, beginning with the Big Bang. Credit: NASA
The timeline of the Universe, beginning with the Big Bang. According to String Theory, this is just one of many possible worlds. Credit: NASA

Scientists believe that the fourth dimension is time, which governs the properties of all known matter at any given point. Along with the three other dimensions, knowing an object’s position in time is essential to plotting its position in the Universe. The other dimensions are where the deeper possibilities come into play, and explaining their interaction with the others is where things get particularly tricky for physicists.

According to Superstring Theory, the fifth and sixth dimensions are where the notion of possible worlds arises. If we could see on through to the fifth dimension, we would see a world slightly different from our own, giving us a means of measuring the similarity and differences between our world and other possible ones.

In the sixth, we would see a plane of possible worlds, where we could compare and position all the possible universes that start with the same initial conditions as this one (i.e., the Big Bang). In theory, if you could master the fifth and sixth dimensions, you could travel back in time or go to different futures.

In the seventh dimension, you have access to the possible worlds that start with different initial conditions. Whereas in the fifth and sixth, the initial conditions were the same, and subsequent actions were different, everything is different from the very beginning of time. The eighth dimension again gives us a plane of such possible universe histories. Each begins with different initial conditions and branches out infinitely (hence why they are called infinities).

In the ninth dimension, we can compare all the possible universe histories, starting with all the different possible laws of physics and initial conditions. In the tenth and final dimension, we arrive at the point where everything possible and imaginable is covered. Beyond this, nothing can be imagined by us lowly mortals, which makes it the natural limitation of what we can conceive in terms of dimensions.

String space - superstring theory lives in 10 dimensions, which means that six of the dimensions have to be "compactified" in order to explain why we can only perceive four. The best way to do this is to use a complicated 6D geometry called a Calabi-Yau manifold, in which all the intrinsic properties of elementary particles are hidden. Credit: A Hanson. String space - superstring theory lives in 10 dimensions, which means that six of the dimensions have to be "compactified" in order to explain why we can only perceive four. The best way to do this is to use a complicated 6D geometry called a Calabi-Yau manifold, in which all the intrinsic properties of elementary particles are hidden. Credit: A Hanson.
The existence of extra dimensions is explained using the Calabi-Yau manifold, in which all the intrinsic properties of elementary particles are hidden. Credit: A Hanson.

The existence of these additional six dimensions, which we cannot perceive, is necessary for String Theory for there to be consistency in nature. The fact that we can perceive only four dimensions of space can be explained by one of two mechanisms: either the extra dimensions are compactified on a very small scale, or else our world may live on a 3-dimensional submanifold corresponding to a brane, on which all known particles besides gravity would be restricted (aka. brane theory).

If the extra dimensions are compactified, then the extra six dimensions must be in the form of a Calabi–Yau manifold (shown above). While imperceptible as far as our senses are concerned, they would have governed the formation of the Universe from the very beginning. Hence why scientists believe that by peering back through time and using telescopes to observe light from the early Universe (i.e., billions of years ago), they might be able to see how the existence of these additional dimensions could have influenced the evolution of the cosmos.

Much like other candidates for a grand unifying theory – aka the Theory of Everything (TOE) – the belief that the Universe is made up of ten dimensions (or more, depending on which model of string theory you use) is an attempt to reconcile the standard model of particle physics with the existence of gravity. In short, it is an attempt to explain how all known forces within our Universe interact and how other possible universes themselves might work.

For additional information, here’s an article on Universe Today about parallel Universes and another on a parallel Universe that scientists thought they’d found, but doesn’t actually exist.

There are also some other great resources online. There is a great video that explains the ten dimensions in detail. You can also look at the PBS website for the TV show Elegant Universe. It has a great page on the ten dimensions.

You can also listen to Astronomy Cast. You might find Episode 137: Large Scale Structure of the Universe very interesting.

Source: PBS

Astronomers Discover First Mulitiple-image Gravitationally-lensed Supernova

The four dots around the bright source, an elliptical galaxy, are multiple images of the new supernova taken with the Hubble Space Telescope between November 10-20, 2014. In the bottom image, the galaxy has been digitally removed to show only the supernova. The line segments are diffraction spikes from a nearby star. Credit: P.L. Kelly et. all

How about four supernovae for the price of one? Using the Hubble Space Telescope, Dr. Patrick Kelly of the University of California-Berkeley along with the GLASS (Grism Lens Amplified Survey from Space) and Hubble Frontier Fields teams, discovered a remote supernova lensed into four copies of itself by the powerful gravity of a foreground galaxy cluster. Dubbed SN Refsdal, the object was discovered in the rich galaxy cluster MACS J1149.6+2223 five billion light years from Earth in the constellation Leo. It’s the first multiply-lensed supernova every discovered and one of nature’s most exotic mirages.

The rich galaxy cluster MACS J1149+2223 gained notoriety in 2012 when the most distant galaxy when the most distant galaxy found to date was discovered there through gravitational lensing.
The lensed supernova was discovered far behind the rich galaxy cluster MACS J1149.6+2223. The cluster is one of the most massive known and gained notoriety in 2012 when astronomers harnessed its powerful lensing ability to uncover the most distant galaxy known at the time. Credit: NASA/ESA/M. Postman STScI/CLASH team

Gravitational lensing grew out of Einstein’s Theory of Relativity wherein he predicted massive objects would bend and warp the fabric of spacetime. The more massive the object, the more severe the bending. We can picture this by imagining a child standing on a trampoline, her weight pressing a dimple into the fabric. Replace the child with a 200-pound adult and the surface of the trampoline sags even more.

Massive objects like the sun and even the planets warp the fabric of space. Here a planet orbits the sun but does not fall in because of its sideways orbital motion.
Massive objects like the Sun and even the planets warp the fabric of space. Here a planet orbits the Sun but doesn’t fall in because of its sideways orbital motion.

Similarly, the massive Sun creates a deep, but invisible dimple in the fabric of spacetime. The planets feel this ‘curvature of space’ and literally roll toward the Sun. Only their sideways motion or angular momentum keeps them from falling straight into the solar inferno.

Curved space created by massive objects also bends light rays. Einstein predicted that light from a star passing near the Sun or other massive object would follow this invisible curved spacescape and be deflected from an otherwise straight path. In effect, the object acts as a lens, bending and refocusing the light from the distant source into either a brighter image or multiple and distorted images. Also known as the deflection of starlight, nowadays we call it gravitational lensing.

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada
This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada


Simulation of distorted spacetime around a massive galaxy cluster over time

Turns out there are lots of these gravitational lenses out there in the form of massive clusters of galaxies. They contain regular matter as well as vast quantities of the still-mysterious dark matter that makes up 96% of the material stuff in the universe. Rich galaxy clusters act like telescopes – their enormous mass and powerful gravity magnify and intensify the light of galaxies billions of light years beyond, making visible what would otherwise never be seen.

Here we see a central slice of the MACS cluster. A massive elliptical galaxy is responsible for splitting SN Refsdal into four images. It also distorts and lenses the purple-toned spiral galaxy that's host to the supernova. Credit:
This cropped image shows the central slice of the MACS J1149 galaxy cluster. A massive elliptical galaxy lenses the light of SN Refsdal into four separate images. It also distorts the purplish spiral galaxy that’s host to the supernova. Credit: NASA/ESA/M. Postman STScI/CLASH team

Let’s return to SN Refsdal, named for Sjur Refsdal, a Norwegian astrophysicist who did early work in the field of gravitational lensing.  A massive elliptical galaxy in the MACS J1149 cluster “lenses” the  9.4 billion light year distant supernova and its host spiral galaxy from background obscurity into the limelight. The elliptical’s powerful gravity’s having done a fine job of distorting spacetime to bring the supernova into view also distorts the shape of the host galaxy and splits the supernova into four separate, similarly bright images. To create such neat symmetry, SN Refsdal must be precisely aligned behind the galaxy’s center.

What looks like a galaxy with five nuclei really has just one (at center) surrounded by a mirage of four images of a distant quasar. The galaxy lies 400 million light years away; the quasar about 8 billion. Credit: NASA/ESA/Hubble
What looks like a galaxy with five nuclei really has just one (at center) surrounded by a mirage of four images of a distant quasar. The galaxy lies 400 million light years away; the quasar about 8 billion. Credit: NASA/ESA/Hubble

The scenario here bears a striking resemblance to Einstein’s Cross, a gravitationally lensed quasar, where the light of a remote quasar has been broken into four images arranged about the foreground lensing galaxy. The quasar images flicker or change in brightness over time as they’re microlensed by the passage of individual stars within the galaxy. Each star acts as a smaller lens within the main lens.

Color-composite image of lensing elliptical galaxy and distorted background  host spiral (top).The green circles show the locations of images S1–S4, while another quadruply imaged segment of the spiral arm is marked in  red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field. Credit: S.L. Kelly et. all
Color-composite image of the lensing elliptical galaxy and distorted background host spiral (top). The green circles, S1-4, show the locations of the supernova images, while another quadruply imaged segment of the spiral arm is marked in red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field.  Talk about a funhouse mirror! Credit: P.L. Kelly/GLASS/Hubble Frontier Fields

Detailed color images taken by the GLASS and Hubble Frontier Fields groups show the supernova’s host galaxy is also multiply-imaged by the galaxy cluster’s gravity. According to their recent paper, Kelly and team are still working to obtain spectra of  the supernova to determine if it resulted from the uncontrolled burning and explosion of a white dwarf star (Type Ia) or the cataclysmic collapse and rebound of a supergiant star that ran out of fuel (Type II).

The time light takes to travel to the Earth from each of the lensed images is different because each follows a slightly different path around the center of the lensing galaxy. Some paths are shorter, some longer. By timing the brightness variations between the individual images the team hopes to provide constraints not only on the distribution of bright matter vs. dark matter in the lensing galaxy and in the cluster but use that information to determine the expansion rate of the universe.

You can squeeze a lot from a cosmic mirage!

New Simulation Offers Stunning Images of Black Hole Merger

A binary black hole system, viewed edge-on. This pair of extremely dense objects twists and warps spacetime as the two black holes spiral in toward one another. Image Credit: Bohn, Throwe, Hébert, Henriksson, Bunandar, Taylor, Scheel (see http://www.black-holes.org/lensing)

A black hole is an extraordinarily massive, improbably dense knot of spacetime that makes a living swallowing or slinging away any morsel of energy that strays too close to its dark, twisted core. Anyone fortunate (or unfortunate) enough to directly observe one of these beasts in the wild would immediately notice the way its colossal gravitational field warps all of the light from the stars and galaxies behind it, a phenomenon known as gravitational lensing.

Thanks to the power of supercomputers, a curious observer no longer has to venture into outer space to see such a sight. A team of astronomers has released their first simulated images of the lensing effects of not just one, but two black holes, trapped in orbit by each other’s gravity and ultimately doomed to merge as one.

Astronomers have been able to model the gravitational effects of a single black hole since the 1970s, but the imposing mathematics of general relativity made doing so for a double black-hole system a much larger challenge. Over the last ten years, however, scientists have improved the accuracy of computer models that deal with these types of calculations in an effort to match observations from gravitational wave detectors like LIGO and VIRGO.

The research collaboration Simulating Extreme Spacetimes (SXS) has begun using these models to mimic the lensing effects of high-gravity systems involving objects such as neutron stars and black holes. In their most recent paper, the team imagines a camera pointing at a binary black hole system against a backdrop of the stars and dust of the Milky Way. One way to figure out what the camera would see in this situation would be to use general relativity to compute the path of each photon traveling from every light source at all points within the frame. This method, however, involves a nearly impossible number of calculations.  So instead, the researchers worked backwards, mapping only those photons that would reach the camera and result in a bright spot on the final image – that is, photons that would not be swallowed by either of the black holes.

A binary black hole system, viewed from above. Image Credit: Bohn et al. (see http://arxiv.org/abs/1410.7775)
The same binary black hole system, viewed from above. Image Credit: Bohn et al. (see http://arxiv.org/abs/1410.7775)

As you can see in the image above, the team’s simulations testify to the enormous effect that these black holes have on the fabric of spacetime. Ambient photons curl into a ring around the converging binaries in a process known as frame dragging. Background objects appear to multiply on opposite sides of the merger (for instance, the yellow and blue pair of stars in the “northeast” and the “southwest” areas of the ring). Light from behind  the camera is even pulled into the frame by the black holes’ mammoth combined gravitational field. And each black hole distorts the appearance of the other, pinching off curved, comma-shaped regions of shadow called “eyebrows.” If you could zoom in with unlimited precision, you would find that there are, in fact, an infinite number of these eyebrows, each smaller than the last, like a cosmic set of Russian dolls.

In case you thought things couldn’t get any more amazing, SXS has also created two videos of the black hole merger: one simulated from above, and the other edge-on.
 



 



The SXS collaboration will continue to investigate gravitationally ponderous objects like black holes and neutron stars in an effort to better understand their astronomical and physical properties. Their work will also assist observational scientists as they search the skies for evidence of gravitational waves.

Check out the team’s ArXiv paper describing this work and their website for even more fascinating images.

Higgs Boson Threatened The Early Universe, But Gravity Saved The Day

Image Credit: Science/AAAS

All the physical properties of our Universe – indeed, the fact that we even exist within a Universe that we can contemplate and explore – owe to events that occurred very early in its history. Cosmologists believe that our Universe looks the way it does thanks to a rapid period of inflation immediately before the Big Bang that smoothed fluctuations in the vacuum energy of space and flattened out the fabric of the cosmos itself.

According to current theories, however, interactions between the famed Higgs boson and the inflationary field should have caused the nascent Universe to collapse. Clearly, this didn’t happen. So what is going on? Scientists have worked out a new theory: It was gravity that (literally) held it all together.

The interaction between the curvature of spacetime (more commonly known as gravity) and the Higgs field has never been well understood. Resolving the apparent problem of our Universe’s stubborn existence, however, provides a good excuse to do some investigating. In a paper published this week in Physical Review Letters, researchers from the University of Copenhagen, the University of Helsinki, and Imperial College London show that even a small interaction between gravity and the Higgs would have been sufficient to stave off a collapse of the early cosmos.

The researchers modified the Higgs equations to include the effect of gravity generated by UV-scale energies. These corrections were found to stabilize the inflationary vacuum at all but a narrow range of energies, allowing expansion to continue and the Universe as we know it to exist… without the need for new physics beyond the Standard Model.

This new theory is based on the controversial evidence of inflation announced by BICEP2 earlier this summer, so its true applicability will depend on whether or not those results turn out to be real. Until then, the researchers are hoping to support their work with additional observational studies that seek out gravitational waves and more deeply examine the cosmic microwave background.

At this juncture, the Higgs-gravity interaction is not a testable hypothesis because the graviton (the particle that handles all of gravity’s interactions) itself has yet to be detected. Based purely on the mathematics, however, the new theory presents an elegant and efficient solution to the potential conundrum of why we exist at all.

What’s Causing The Universe To Expand?

What's Causing The Universe To Expand?

We’ve all heard that the Universe is expanding, but why is it expanding? What’s the force pushing everything outwards?

If still you don’t know that we live in an expanding Universe, then I’m clearly not doing my job.

And so once more, with feeling… the Universe is expanding. But that certainly doesn’t answer all the questions that go along with the it.

Like what’s the Universe expanding into? Which we did in another video, which I’ll list at the end of this episode. You might also want to know why is the Universe expanding? What’s making this happen? Did it give up its gym membership? Did it sign up for the gallon of ice cream of the month club? Has it completely embraced the blerch?

Edwin Hubble, the astronomer made famous by being named after a space telescope, provided the definitive evidence that the Universe was expanding. Observing distant galaxies, he observed they were fleeing outwards, in fact he was able to come up with calculations to show just how fast they were moving away from us.

Or to be more precise, he was able to show how fast all the galaxies are moving away from each other. Which was your question! Just like a minute ago! See you’re just as smart as Hubble!

So up until about 15 years ago, the only answer was momentum. The idea was that the Universe received all the energy it needed for its expansion in the first few moments after the Big Bang.

Imagine the beginning of the Universe, BOOM, like an explosion from a gun. And all the rest of the expansion is the Universe coasting outwards. For the longest time, astronomers were trying to figure out what this momentum would mean for the future of the Universe.

Dark Energy
The Hubble Space Telescope image of the inner regions of the lensing cluster Abell 1689 that is 2.2 billion light?years away. Light from distant background galaxies is bent by the concentrated dark matter in the cluster (shown in the blue overlay) to produce the plethora of arcs and arclets that were in turn used to constrain dark energy. Image courtesy of NASA?ESA, Jullo (JPL), Natarajan (Yale), Kneib (LAM)

Would the mutual gravity of all the objects in the Universe cause it to slow to a halt at some point in the distant future, or maybe even collapse in on itself, leading to a Big Crunch? Or just clump up in piles and stay on the couch all summer because it’s maybe a little lazy and isn’t ready to start going back to the gym yet?

In 1999, astronomers discovered something completely unexpected… dark energy. As they were doing their observations to figure out exactly how the Universe would coast to a stop, they discovered that it’s actually speeding up. It’s as if that bullet is actually a rocket and it’s accelerating.

Now it appears that the Universe will not only expand forever, but the speed of its expansion will continue to accelerate faster and faster. So what’s causing this expansion? Currently, we believe it’s mostly momentum left over from the Big Bang, and the force of dark energy will be accelerating this expansion. Forever.

How do you feel about a rapidly accelerating expanding Universe? Tell us in the comments below.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Why Doesn’t The Sun Steal The Moon?

On Sept. 18, 1977, Voyager 1 took three images of the Earth and Moon that were combined into this one image. The moon is artificially brightened to make it show up better. Credit: NASA

The Sun has so much more mass than the Earth. So, so, so much more mass. Almost everything in the Solar System is orbiting the Sun, and yet, the Moon refuses to leave our side. What gives?

The Sun contains 99.8% of the entire mass of the Solar System. It looks to us like everything seems to orbit the Sun, so why doesn’t the Sun capture the Moon from Earth like a schoolyard bully snatching the Earth’s lunch money. That would make sense right? It all fits in with our skewed view of social hierarchy based on an entities volume.

Good news! It’s already happened, In a way. The Sun has already captured the Moon. If you look at the orbit of the Moon, it orbits the Sun similar to the way Earth does. Normally the motion of the Moon around the Sun is drawn as a kind of Spirograph pattern, but its actual motion is basically the same orbit as Earth with a small wobble to it.

The Moon also orbits the Earth. You might think this is because the Earth is much closer to the Moon than the Sun. After all, the strength of gravity depends not only on the mass of an object, but also on its distance from you. But this isn’t the case. The Sun is about 400 times more distant from the Moon than the Earth, but the Sun is about 330,000 times more massive.

If you’re up for some napkin calculations, you little mathlete, by using Newton’s law of gravity, you find that even with its greater distance, the Sun pulls on the Moon about twice as hard as the Earth does.
So why can’t the Moon escape the Earth?

In order to escape the gravitational pull of a body, you need to be moving fast enough *relative to that body* to escape its pull. This is known as the escape velocity of the object.

It takes two to tango. The moon’s gravity raises a pair of watery bulges in the Earth’s oceans creating the tides, while Earth's gravity stretches and compresses the moon to warm its interior. Illustration: Bob King
It takes two to tango. The moon’s gravity raises a pair of watery bulges in the Earth’s oceans creating the tides, while Earth’s gravity stretches and compresses the moon to warm its interior. Illustration: Bob King

So, yes, the Sun is totally trying to rip the Moon away from the Earth, but the Earth is super clingy.
The speed of the Moon around the Earth is about 1 km/s. At the Moon’s distance from the Earth, the escape velocity is about 1.2 km/s. The Moon simply isn’t moving fast enough to escape the Earth.

Man, those numbers sure are close. I wonder if we could kickstart a rocket to stick on the side? So, even though the Moon can’t escape the Earth, it is gradually moving away. This is due to the tidal interactions between the Earth and Moon, which we talk about another video we’ll link at the end of this one.

So even though the Moon will never escape the Earth, it will continue to move away. So, what do you think? What kind of devious project should we start to get the Moon that little boost so it finally escapes the clingy Earth and all its clingy Klingon clingyness? Tell us in the comments below.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Review: In “Interstellar,” Christopher Nolan Shows He Has The Right Stuff

Mathew McConnaughey wades through an ocean on another planet. This is not a fishing expedition. He is out to save his children and all humanity. Image courtesy Paramount.

Science fiction aficionados, take heed. The highly-anticipated movie Interstellar is sharp and gripping. Nolan and cast show in the end that they have the right stuff. Nearly a three hour saga, it holds your attention and keeps you guessing. Only a couple of scenes seemed to drift and lose focus. Interstellar borrows style and substance from some of the finest in the genre and also adds new twists while paying attention to real science. If a science-fiction movie shies away from imagining the unknown, taking its best shot of what we do not know, then it fails a key aspect of making sci-fi. Interstellar delivers in this respect very well.

Jessica Chastain, the grown daughter of astronaut McConnaughey starts to torch the cornfields. Interstellar viewers are likely to show no sympathy to the ever present corn fields.
Jessica Chastain, the grown daughter of astronaut McConnaughey takes a torch to the cornfields. Interstellar viewers are likely to show no sympathy to the ever present corn fields. Image courtesy Paramount.

The movie begins quite unassuming in an oddly green but dusty farmland. It does not rely on showing off futuristic views of Earth and humanity to dazzle us. However, when you see a farming family with a dinner table full of nothing but variations of their cash crop which is known mostly as feedstock for swine and cattle, you know humanity is in some hard times. McConaughey! Save us now! I do not want to live in such a future!

One is left wondering about what got us to the conditions facing humanity from the onset of the movie. One can easily imagine a couple of hot topic issues that splits the American public in two. But Nolan doesn’t try to add a political or religious bent to Interstellar. NASA is in the movie but apparently after decades of further neglect, it is literally a shadow of even its present self.

Somehow, recent science fiction movies — Gravity being one exception — would make us believe that the majority of American astronauts are from the Midwest. Driving a John Deere when you are 12, being raised under big sky or in proximity to the home of the Wright Brothers would make you hell-bent to get out of Dodge and not just see the world but leave the planet. Matthew McConaughey adds to that persona.

Dr. Kip Thorne made it clear that black is not the primary hue of Black Holes. His guidance offered to Nolan raised science fiction to a new level.
Dr. Kip Thorne made it clear that black is not the primary hue of Black Holes. His guidance offered to Nolan raised science fiction to a new level. Image courtesy Paramount.

We are seemingly in the golden age of astronomy. At present, a science fiction movie with special effects can hardly match the imagery that European and American astronomy is delivering day after day. There is one of our planets that gets a very modest delivery in Interstellar. An undergraduate graphic artist could take hold of NASA imagery and outshine those scenes quite easily. However, it appears that Nolan did not see it necessary to out-do every scene of past sci-fi or every astronomy picture of the day (APOD) to make a great movie.

Nolan drew upon American astro-physicist Dr. Kip Thorne, an expert on Einstein’s General Relativity, to deliver a world-class presentation of possibly the most extraordinary objects in our Universe – black holes. It is fair to place Thorne alongside the likes of Sagan, Feynman, Clarke and Bradbury to advise and deliver wonders of the cosmos in compelling cinematic form. In Instellar, using a black hole in place of a star to hold a planetary system is fascinating and also a bit unbelievable. Whether life could persist in such a system is a open question. There is one scene that will distress most everyone in and around NASA that involves the Apollo Moon landings and one has to wonder if Thorne was pulling a good one on old NASA friends.

Great science fiction combines a vision of the future with a human story. McConaughey and family are pretty unassuming. John Lithgow, who plays grandpa, the retired farmer, doesn’t add much and some craggy old character actor would have been just fine. Michael Cane as the lead professor works well and Cane’s mastery is used to thicken and twist the plot. His role is not unlike the one in Children of Men. He creates bends in the plot that the rest of the cast must conform to.

There was one piece of advice I read in previews of Interstellar. See it in Imax format. So I ventured over to the Imax screening at the Technology Museum in Silicon Valley. I think this advice was half correct. The Earthly scenes gained little or nothing from Imax but once they were in outer space, Imax was the right stuff. Portraying a black hole and other celestial wonders is not easy for anyone including the greatest physicists of our era and Thorne and Nolan were right to use Imax format.

According to industry insiders, Nolan is one of a small group of directors with the clout to demand film recording rather than digital. Director Nolan used film and effects to give Interstellar a very earthy organic feel. That worked and scenes transitioned pretty well to the sublime of outer space. Interstellar now shares the theaters with another interesting movie with science fiction leanings. The Stephen Hawking biography, “The Theory of Everything” is getting very good reviews. They hold different ties to science and I suspect sci-fi lovers will be attracted to seeing both. With Interstellar, out just one full day and I ran into moviegoers that had already seen it more than once.

Where does Interstellar stand compared to Stanley Kubricks works? It doesn’t make that grade of science fiction that stands up as a century-class movie. However, Thorne’s and Nolan’s accounting of black holes and worm holes and the use of gravity is excellent. Instellar makes a 21st Century use of gravity in contrast to Gravity that was stuck in the 20th Century warning us to be careful where you park your space vehicle. In the end, Matthew McConaughey serves humanity well. Anne Hathaway plays a role not unlike Jody Foster in Contact – an intellectual but sympathetic female scientist.

Jessica Chastain playing the grown up daughter of McConaughey brings real angst and an edge to the movie; even Mackenzie Foy playing her part as a child. Call it the view ports for each character – they are short and narrow and Chastain uses hers very well. Matt Damon shows up in a modest but key role and does not disappoint. Nolan’s directing and filmography is impressive, not splashy but one is gripped by scenes. Filming in the small confines of spaceships and spacesuits is challenging and Nolan pulls it off very well. Don’t miss Interstellar in the theaters. It matches and exceeds the quality of several recent science fiction movies. Stepping back onto the street after the movie, the world seemed surprisingly comforting and I was glad to be back from the uncertain future Nolan created.

Could A Planet Be as Big as a Star?

Could A Planet Be as Big as a Star?

How big do planets get? Can they get star sized?

Everybody wants the biggest stuff.

Soft drink sizes, SUV’s, baseball caps, hot dogs and truck nuts.

Astronomers mostly measure stars in terms of mass and use the Sun as a yard stick. This star is 3 solar masses, that star is 10 solar masses, and so on.

We’re pandering to those of you who want the most massive stuff as opposed to the most volumetric stuff. So if you want the biggest truck, but don’t care if it’s got the most truck atoms in one place, this might not be for you.

How massive can planets get, and where can I order a custom one more massive than a star?

It all depends on what your planet is made of. There are two flavors of planets, gas and rock.

Gas planets, like Saturn and Jupiter are pretty much made of the same stuff as our Sun.

Jupiter’s pretty big, but it’s actually only about 1/1000th the mass of our star. If you made it more massive. by crashing about 80 Jupiters together, you’d get the same amount of mass as the smallest possible red dwarf star.

And all that mass would compress and heat up the core and it would ignite as a star.

Artist's View of Extrasolar Planet HD 189733b
Artist’s View of Extrasolar Planet HD 189733b

Extrasolar planet astronomers have turned up some pretty massive gas planets. The most massive so far contains 28.7 times the mass of Jupiter.

That’s so massive it’s more like a brown dwarf.

But if you had a planet entirely made of rock, like the Earth. It would need to be much, much larger before its core would ignite in fusion.

It would need to be dozens of times the mass of our Sun.

Stars with 8-11 stellar masses can fuse silicon. So a rocky planet would need millions of times the mass of the Earth before it would have that kind of pressure and temperature.

So you could get a situation where you have more mass than the Sun in a rock flavored world, and it wouldn’t ignite as a star. It would get pretty warm though.

No star can burn iron. In fact, when stars develop iron in their core, that’s when they shut down suddenly and you get a supernova.

Feel free to collect all the iron in the Universe together and lump it into a ridiculously huge pile and no matter how long you stare at for, it’ll never boil or turn into a star.

It might turn into a black hole, though.

Artist's impression of Kepler-10c (foreground planet)
Artist’s impression of Kepler-10c (foreground planet)

The largest rocky planet ever discovered is Kepler 10c, with 17 times the mass of Earth.

Massive, but nowhere near the smallest star.

There’s new research that says that heavier elements blasted out of supernovae might collect within huge star forming nebulae, like gold in the eddies of a river. This metal could collect into actual stars. Perhaps 1 in 10,000 stars might be made of heavier elements, and not hydrogen and helium.

Metal stars.

So, it’s theoretically possible. There might be corners of the Universe where enough metal has collected together that you could end up with a star that’s made up of planety stuff. And that’s pretty amazing.

What do you think? If we found one of these giant metal stars, what should we call it?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!