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Ngumi Mirie
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How We See the Stars in 3D

Astronomers can measure the distance to about a billion stars using the same effect that lets you enjoy a 3D summer blockbuster.

There are lots of clues our minds use to determine whether something is close to us or far away, such as its apparent size, its position relative to other objects and its motion. But since humans typically have two eyes, we can also gauge an object’s distance using an effect known as parallax. When you walk along a sidewalk, you’ll notice that closer objects appear to move past you more quickly than more distant objects. This means that if you look at an array of objects from two slightly different positions, the closer objects will appear to have shifted more than distant objects. Since your eyes have different positions, each eye gets a slightly different view of the world, and closer objects will appear more different than farther objects. Our brains combine these two views to give us a 3D view of the world.

3D movies take advantage of this effect to give an “in your face” movie experience. Rather than filming one movie, directors of 3D movies film two, where each movie is filmed from a slightly different perspective (typically the same separation as human eyes). Once in the theater, the two perspectives are shown together. By itself that would just make for a blurry movie, so they are shown on a special screen so that the light reflected from one projector is polarized differently than the other. Polarization is a property of light orientation that our eyes don’t typically notice, but polarized light can be blocked by things like polarized sunglasses.

This is why you have to wear special glasses in a 3D movie. These glasses are similar to sunglasses, but each lens blocks a different orientation of light. This ensures that each of your eyes only sees one of the two movies. Since each movie has a different perspective, your eyes have different views similar to the real world, and your brain integrates them as a perception of depth.

So how does this effect work for stars? You don’t notice any depth to the night sky because your depth perception only works for a distance of about 6 meters (20 feet), and the stars are light years away. But because the Earth revolves around the Sun, our view of the stars changes slightly over the course of a year. So over the course of a year the closer stars will appear to shift relative to more distant stars. This shift is incredibly small. If you held a single sheet of paper edge-on at arm’s length, the thickness of the paper would be about three times wider than the largest shift of the closest star.

Astronomers have been able to measure the parallax of the closest stars for 80 years. We’re now able to measure stellar distances to more than 1,600 light years. The Hipparcos spacecraft, for example, measured the distances of about 2.5 million stars to varying degrees of accuracy. The Gaia spacecraft is expected to measure the distances of a billion stars.

As impressive as that is, you might be wondering how we measure the distances of farther stars? After all, our galaxy alone is 100,000 light years across. That’s an interesting story for another time.
Astronomers can measure the distance to about a billion stars using the same effect that lets you enjoy a 3D summer blockbuster.
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Brian Koberlein:

To prove dark energy is real we have to measure redshift and distance independently, and that takes a bit of doing.

Measuring redshift is fairly straightforward. By comparing the spectrum of a distant galaxy with the known spectra of atoms and molecules here on Earth, we can determine the amount of redshift expressed in a quantity known as z. To measure distance, however, we need to use observations of a kind of supernova known as type Ia. These are often described as “standard candles” that always explode with the same brightness, but that isn’t actually the case. Some type Ia supernovae are brighter than others, so you can’t simply use their observed brightness as a measure.

[...]

Recent observations of a large number of supernovae seem to show two classes of type Ia supernovae, with slightly different ratios. If this is true, then it could readjust the amount of dark energy the universe has. However this would be a minor adjustment to our understanding of cosmology, not a revolutionary change. While supernovae are a great way to observe the effects of dark energy, they aren’t the only way. We can also look at things such as the clustering of galaxies on large scales, and the fluctuations within the cosmic microwave background to determine the amount of dark energy in the universe. What we find is that they all agree reasonably well.

So while type Ia supernovae aren’t standard candles, they are standardizable candles

https://briankoberlein.com/2015/07/22/standardizing-the-candle/
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Forewarned is Forearmed

Before the new flurry of hyped articles about the EMDrive/Hyperdrive burn through the web again, here is the last paragraph of the research article being referred to:

The nature of the thrusts is still unclear. Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive but intends to assess possible side-effects in the methods used so far. Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation. At worst case we may find how to effectively shield thrust balances from magnetic fields.

Translation:
New results are interesting, but inconclusive.
This should be looked at further.

The author of any article claiming the EMDrive has been confirmed is either lying or hasn't read the paper.
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A Galaxy in the Making

New observations from ALMA show a galaxy in the making.

ALMA observes the universe at millimeter wavelengths, so it’s particularly good at seeing emissions from cold gasses such as carbon. In this case a team observed carbon gas around a galaxy with a redshift of about z = 7. This means we’re seeing the galaxy from a time when the universe was only about a billion years old. What’s striking about the carbon gas is that it’s off-center from the galaxy. This is likely means the gas is being accreted from the intergalactic medium, while the galaxy itself undergoes a period of rapid star production.

This is the first time we’ve been able to see dynamic behavior in an early galaxy. It’s important because it helps us understand the period known as reionization, when the first stars and galaxies began to illuminate the cosmos.
New observations from ALMA show a galaxy in the making.
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Along the Line

In the 1800s astronomers began to light from the Sun through a diffraction grating, which allowed them to view the Sun’s spectral lines. Thus began an area of astronomy known as spectroscopy. As the technology advanced enough to look at the spectra of stars, we were finally able to categorize stars by not just their temperatures, but by the elements contained in their atmospheres. We could also use the shift of these spectra due to the Doppler effect to determine a star’s motion. With modern telescopes we can do the same for galaxies using a method known as long-slit spectroscopy.

The idea of long-slit spectroscopy is to only observe the spectrum of an object along a narrow line. In the case of galaxies, this is typically along its long edge when a galaxy is viewed from mostly edge on. In this way we can look at the spectrum all along a galaxy. Because spectral lines are shifted toward the red or blue due to the motion of the source, the rotation of a galaxy gives a spectral line a shift. From this we can determine the motion of stars in the galaxy. This allows us to study things such as dark matter, which can affect the motion of stars.

Long-slit spectroscopy also allows us to study things such as the evolution of galaxies over time, and how the composition of stars can vary based upon their distance from the galactic core. Given how faint galaxies are compared to many stars, it’s actually a pretty amazing type of astronomy.
The idea of long-slit spectroscopy is to only observe the spectrum of an object along a narrow line. From this we can see the motion of stars in the galaxy.
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Hiding In Plain Sight

Our Milky Way galaxy is more than 100,000 light years across, and contains more than 200 billion stars. An ultracompact dwarf galaxy has only about 100 million stars, but they are packed into a region only 200 light years across. In such a galaxy you might see a million stars with the naked eye.

The first ultracompact dwarf galaxy (UCD) was discovered last year. Since then a handful of others have been found. From these new discoveries we now have an idea of how they could have formed. UCDs are not only extremely dense with stars, but at least one has a supermassive black hole in its core. This black hole is of a size typically found in larger galaxies like our Milky Way. So it’s thought that UCDs were once larger galaxies that have been stripped of their outer stars due to a gravitational collision with another galaxy, as simulated in the video. There are two clues that support this idea. The first is that these ultracompact dwarfs are each found near a large galaxy that could have stripped away outer stars. The second is that UCDs contain higher than expected amounts of iron in their spectra. Iron is more readily produced in larger galaxies, so this points to UCDs once being a large galaxy. If this idea is true, then the other UCDs should also have supermassive black holes, which will be a focus of future study.

These compact galaxies are both bright and dense, so they are actually pretty easy to observe. Since we didn’t expect such galaxies to exist, they weren’t really noticed until we knew what to look for. Which just goes to show that sometimes a new discovery can be hiding in plain sight.

Paper: Michael A. Sandoval, et al. Hiding in plain sight: record-breaking compact stellar systems in the Sloan Digital Sky Survey. Astrophysical Journal Letters, 808, L32. (2015)
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Northern Lights on a Distant World

Brown dwarfs are like the Pluto of stars. While they are large enough to produce heat like a star, they are not large enough to fuse hydrogen in their cores like our Sun and other stars. They typically have a mass between 20 and 70 Jupiters, and one of the central questions has been whether they are more planet-like or star-like. New research published in Nature points to a more planetary nature by discovering bright aurora on a brown dwarf. 

Aurora, commonly known as northern lights, occur when high energy charged particles strike the Earth’s upper atmosphere, causing it to glow. They occur largely at the polar regions because of an interaction between the charged particles and the Earth’s magnetic field. While they are common on Earth, they are also found on other planets like Jupiter that have a strong magnetic field. Stars, on the other hand, don’t have aurora.

We’ve known for quite a while that the surface temperatures are rather cool. The most massive brown dwarfs can have temperatures about half that of the Sun, while the smallest brown dwarfs can have surface temperatures no warmer than an oven. But whether their atmospheres are more like that of stars or planets has been an unanswered question.  In this new work, the team noticed a brown dwarf that emitted bursts of strong radio energy about once every 2.8 hours. This pulsar-like behavior could be caused by charged particles interacting with the dwarf’s strong magnetic field, or it could be due to interactions with its atmosphere. To find out the team observed the object in the visible spectrum. What they found was that the spectrum matched that of hydrogen that has been struck by charged particles. In other words, these bursts are due to very bright aurora.

This is the first case of aurora being observed on an object outside our solar system. Combined with other research that shows brown dwarfs can have clouds, it’s clear that the atmospheres of brown dwarfs are more planet-like than star-like.

Paper: G. Hallinan et al. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence. Nature. Vol. 523, p. 568. doi: 10.1038/nature14619 (2015)
Brown dwarfs are like the Pluto of stars. New research published in Nature points to a more planetary nature by discovering bright aurora on a brown dwarf.
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What If Light Had No Speed Limit?

What would the universe be like if the speed of light were infinite? It might seem like a silly question, since the speed of light clearly isn’t infinite, but questions like these are a good way to explore how different aspects of a physical model are interrelated.

For example, in our universe light is an electromagnetic wave. It not only has a speed, but a wavelength. If you think of a wave as an oscillation, then at infinite speed light would have no time to oscillate. So infinite light can’t be a wave. Since the wavelength of light determines its color, that would also mean it has no color. But it gets worse because in classical physics light is produced when electromagnetic waves cause the charges in atoms and molecules to oscillate. Without waves, atoms can’t be induced to emit light, the universe would be a sea of darkness.

But real light actually has both wave and particle aspects, so let’s suppose that for infinite light it’s just some kind of particle so we can still have light and color without all that meddling wave business. What else would change?

Relativity is an obvious choice. Einstein’s theory of relativity depends upon a finite speed of light. With an infinite light speed, all those fun things like time dilation are thrown out the window. So is Einstein’s most famous equation, E = mc2. The main consequence of this equation is that matter can be transformed into energy and vice versa. It’s central to things like nuclear fusion, which powers the stars and creates the heavy elements. Stars could still be powered by gravitational contraction, but they would only last for a million years rather than billions of years. They also wouldn’t have any mechanism to explode as supernovae, so there would be no way to make new stars from old ones.

Since Einstein’s theory of gravity is a generalization of special relativity, it goes away too. Our model of the universe, beginning with a big bang and expanding through dark energy, depends upon Einstein’s theory. Without it the universe look very different. No dark energy, possibly no big bang.

Of course this is all just a game of pretend. If you made different assumptions about physical phenomena you would derive different effects. We have no way of knowing what an infinite light speed universe would really be like. But what this shows is just how interconnected different aspects of a physical model actually are. Any tweak to the model has consequences that can ripple into widely different areas, or even cause an entire model to collapse.
What would the universe be like if the speed of light were infinite?
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Forewarned is Forearmed

Before the new flurry of hyped articles about the EMDrive/Hyperdrive burn through the web again, here is the last paragraph of the research article being referred to:

The nature of the thrusts is still unclear. Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive but intends to assess possible side-effects in the methods used so far. Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation. At worst case we may find how to effectively shield thrust balances from magnetic fields.

Translation:
New results are interesting, but inconclusive.
This should be looked at further.

The author of any article claiming the EMDrive has been confirmed is either lying or hasn't read the paper.
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A Failure to Communicate

Have you heard about the coming ice age? You may have seen articles with titles such as “Thanks To Reduced Solar Activity, We Could Be Heading For A Mini Ice Age In 2030.” and “‘Mini Ice Age’ Not a Reason to Ignore Global Warming.” Of course such sensational headlines led to rebuttal articles such as “No, We Aren’t Heading Into A ‘Mini Ice Age’” Once again, a hyped headline is used to drive page views, and which only serves to mislead readers. Hence a follow up article on how “The ‘Mini Ice Age’ Hoopla Is A Giant Failure Of Science Communication.” Here’s the thing, though. All of these articles are from IFLS also known as “I’ll use profanity in my website title so people will think I’m edgy and cool.”

You might think IFLS just made a mistake and then made an honest effort to correct it. They didn’t. After their first article hit the press, there were soon legitimate science communicators writing rebuttals. It was clear from the get-go that the research presented did not support a mini ice age in 2030, but IFLS printed it anyway. They published their second article to double down on their hyped claims. Of course, once it was crystal clear that IFLS was wrong, they could have made a correction in the original article and linked to one of the better rebuttals. They didn’t. Instead, they retitled their second article “There Probably Won’t Be A “Mini Ice Age” In 15 Years” and linked to that at the bottom of the page. To this date, they still haven’t made clear that their first article is in error. Why correct your “mistakes” when your lies get you nearly 76,000 likes on Facebook? The last two articles aren’t even ones IFLS wrote. They were actually written on The Conversation and then reprinted on IFLS. Heaven forbid you direct traffic to another site.

This isn’t a failure in science communication. It is the willful promotion of ignorance. So I think a new name for the site is in order: “We’re Just Interested In Pageviews. The Science Can F Itself.”

HT to Yvette d’Entremont for pointing these articles out.
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Earth 2

NASA has announced confirmation of the most Earth-like planet yet. Known as Kepler-452b, it is a “super Earth” about 60% larger than our home planet. We don’t know its mass, but if it has a similar composition to Earth, then its mass is about 4 times Earth’s, and its surface gravity is about 1.6 gees. While that’s not too similar to Earth, what’s remarkable is its orbit. Kepler is a G2 star only 4% more massive than our own Sun, and this new planet orbits at a radius only 5% larger than Earths. The amount of light 452b receives from its star is almost identical to Earth.

We don’t have any direct evidence regarding 452b’s composition. It could be a cold dry world like Mars, or have a thick and toxic atmosphere like Venus. But it could also be a wet world with an atmosphere similar to ours. If that’s the case, then it would have a temperature similar to Earth’s, with liquid water lakes or oceans. It could have a strong magnetic field and be geologically active. It is within the realm of possibility that the planet would be habitable by terrestrial organisms. Kepler 452 is about 1.5 billion years older than our Sun, so this newly announced planet has been within the habitable zone of its star for 6 billion years, which is plenty of time for life to have evolved.

It’s important not to read too much into this. Kepler-452b could be completely inhospitable for lots of reasons, and we still don’t know if it is easy or difficult for life to arise on potentially habitable worlds. But this discovery does make one thing quite clear. Sun-like stars do indeed have Earth-like planets orbiting their habitable zones. Given the statistics of the exoplanets we’ve found thus far, such planets appear to be common. Perhaps extraordinarily so.
NASA has announced confirmation of the most Earth-like planet yet.
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Origin.The ancient Egyptian name,Meri-Amun,meaning "beloved of the sun god Amun"when adopted by the Isralites was recorded in the bible as Miriam.The sister of the famous Moses who led the Isralites to the promised land of Canaan was called Miriam.The Latin adopted the name as Maria which form appears in most Western European languages.Mary is the English Bible Version.The Ethiopia versions Maryam and Mariam unlike in Europe where it is a female baptisimal name have been used as patronymics/surnames for ages.Some examples of well known Ethiopians with the patronymic are;Emporor Takla Maryam(1430-1433) of the Solomonic Dynasty,Emporor Baeda Maryam (1468-1478) and more recently Mengistu Haile Mariam who was head of state between 1977 and 1991.And the current Ethiopian Prime Minister HailleMariam Desalegn.The introduction of the name to giküyüland(Central Kenya)came about either in the late 1700s or early 1800s during the period in Ethiopian history reffered to as Zamana Masafint or" Era of the Prince" when there was protracted conflicts between the many claimants of the seat of the emporor populary known as the king of kings(Nègusa Nagäst)Among the group of royals who escaped the terror of Ras Sehul the powerful Tigrean Warlord were several women with the title Waizero.One of the women,escorted by some men among them Kassa and Tefere reached an area now known as Dagorreti and settled there.The woman was carrying a boy whose name was Mariam which the Agiküyü adopted as Miríí.Though Waizero was a title(Married Woman or the equivalent of Dame in the court titles of Ethiopian Nobility) the Agiküyü were not to know that and they called her Waithera,so,the boy grew up to be known as Miríí wa Waithera and is the originator of the family by the name Mbari ya Mirie.The boy is my anscestor and it is partly the reason why I have a fairer skin color than most kikiyus.
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Able to relate to matters of science while lifting weights.I know a thing or two about the origin of the universe and at my weight of 152lbs(70 Kgs) My PB deadlift is 330lbs(150 Kgs) and I am aiming a bit higher than that.
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