Welcome to the night sky report for May 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. In May, we are looking away from the crowded, dusty plane of our own galaxy, toward a region where the sky is brimming with distant galaxies. Locate Virgo to find a concentration of roughly 2000 galaxies. Then search for Coma Berenices to identify many more. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
What makes up the tenuous gas and dust that pervades our galaxy, filling the space between stars? What kinds of complex molecules form naturally in our universe? Where might these molecules form? And how are they distributed throughout space? Over the vast, empty reaches of interstellar space, countless small molecules tumble quietly though the cold vacuum. Forged in the fusion furnaces of ancient stars and ejected into space when those stars exploded, these lonely molecules account for a significant amount of all the carbon, hydrogen, silicon, and other atoms in the universe. In fact, some 20 percent of all the carbon in the universe is thought to exist as some form of interstellar molecule. Many astronomers hypothesize that these interstellar molecules are responsible for an observed phenomenon on Earth known as "diffuse interstellar bands," spectrographic proof that something out there in the universe is absorbing certain distinct colors of light from stars before it reaches the Earth. But since we don't know the exact chemical composition and atomic arrangements of these mysterious molecules, it remains unproven whether they are, in fact, responsible for the diffuse interstellar bands. Now, from a jumble of confusing clues in Hubble observations, scientists have picked out evidence of a celebrity molecule in interstellar space – the soccer-ball shaped ionized Buckminsterfullerene molecule, or buckyballs.
Magnetars are some of the most extreme objects in the Universe. They are extremely compact objects with masses like our Sun, but with radii of only about 12 miles. One teaspoon of neutron star/magnetar matter weighs as much as Mount Everest. Magnetars generate extremely powerful magnetic fields -- the most intense magnetic fields observed in the Universe. When two neutron stars merge to become a magnetar, the resulting magnetic field is a quadrillion (that is, a million billion) times stronger than the magnetic field that deflects compass needles at the Earth's surface. The field strength is so intense that it heats the surface to 18 million degrees Fahrenheit. Magnetars are born rotating very quickly, which causes their magnetic fields to get amplified. But after a few thousand years, their intense magnetic field slows their spin to a more moderate period of one rotation every few seconds. The magnetic fields both inside and outside the star twist, however, and according to the theory, these intense fields can stress and move the crust much like shearing along the San Andreas Fault in California. The shear moves the crust around along with the magnetic fields tied to the crust, generating twists in the magnetic field that can sometimes break and reconnect in a process that sends trapped positrons and electrons flying out from the star, annihilating each other in a gigantic explosion of X-rays and hard gamma rays. By observing an outburst of these X-ray emission from a galaxy approximately 6.5 billion light years away, researchers found that this was due to the merger of two neutron stars to produce a magnetar. Based on this observation, the researchers were able to calculate that mergers like this happen roughly 20 times per year in each region of a billion light years cubed.
M87 (also known as Virgo A or NGC 4486) is one of the most massive galaxies in the local Universe. To give you an idea of its size, M87 has a large population of globular clusters (about 12,000) compared with the 150 to 200 orbiting our Milky Way galaxy. It also has a jet of energetic plasma traveling at relativistic speed that originates at the core and extends at least 4900 light-years. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers. As in most, if not all, spiral galaxies, M87 has a supermassive black hole at its center. Black holes are extraordinary cosmic objects with enormous masses but extremely compact sizes. The extreme density of these objects affects their immediate environment in peculiar ways, warping space-time and super-heating any surrounding material. To date, no one has ever imaged a black hole. But that has now changed with the Event Horizon Telescope (EHT), a planet-scale array of eight ground-based radio telescopes forged through an international collaboration. The EHT was designed specifically to capture images of a black hole. In coordinated press conferences across the globe, EHT researchers revealed the first direct visual evidence of a supermassive black hole and its shadow. The image shows the black hole at the center of M87.
Welcome to the night sky report for April 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. Clear April nights are filled with starry creatures. Look for the Great Bear and Leo the Lion. You can also spot galaxies like M101, M81, and M82. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard… Let’s follow the advice of James Marshall Hendrix (apparently a fellow admirer of the heavens), who famously proclaimed "Excuse me while I kiss the sky."
An international team of researchers has put a theory speculated by the late Stephen Hawking to its most rigorous test to date, and their results have ruled out the possibility that primordial black holes smaller than a tenth of a millimeter make up most of dark matter. Scientists “know” that 85 percent of the matter in the Universe is made up of dark matter. Its gravitational force prevents stars in our Milky Way from flying apart. However, attempts to detect such dark matter particles using underground experiments, or accelerator experiments including the world’s largest accelerator, the Large Hadron Collider, have failed so far. This has led scientists to consider Hawking's 1974 theory of the existence of primordial black holes, born shortly after the Big Bang, and his speculation that they could make up a large fraction of the elusive dark matter scientists are trying to discover today. The team’s results showed primordial black holes can contribute no more than 0.1 percent of all dark matter mass. Therefore, it is unlikely the theory is true.
Aristotle described the five basic human senses as vision, hearing, taste, smell, and touch. Now, it seems we can add another sense – magnetoreception. Many animals have magnetoreception, so why not humans? Honeybees, salmon, turtles, birds, whales, and bats use the geomagnetic field to help them navigate, and dogs can be trained to locate buried magnets. Apparently, many humans are also able to unconsciously detect changes in Earth-strength magnetic fields, according to scientists at Caltech and the University of Tokyo.
The rotation of stars in galaxies like our Milky Way is puzzling. The orbital speed of stars should decrease with their distance from the center of the galaxy, but in fact stars in the middle and outer regions of galaxies have the same rotational speed. This may be due to the gravitational effect of matter that we can't see. Although researchers have been seeking it for decades, the existence this imaginary construct referred to as “Dark Matter” has yet to be definitively proven -- We still don't know what it is made of or even if it exists at all. With this in mind, physicists in Germany have suggested that the rotational dynamics of galaxies might be explained by other factors. They hypothesize that the mass of photons, which are particles of light, might be responsible. The mass of a photon is extremely small and is usually ignored when analyzing atomic and nuclear processes. However, such a vanishingly tiny mass could have an effect on large-scale astrophysical phenomena.
We can't put the whole Milky Way Galaxy on a scale, but astronomers have been able to come up with one of the most accurate measurements yet of our galaxy's mass. Curious astronomers teamed up the Hubble Space Telescope and European Space Agency's Gaia satellite to precisely study the motions of globular star clusters that orbit our galaxy like bees around a hive. The faster the clusters move under the entire galaxy's gravitational pull, the more massive it is. The researchers concluded the galaxy weighs 1.5 trillion solar masses (one solar mass is the mass of our Sun). However most of it locked up in dark matter. The new mass estimate puts our galaxy on the beefier side, compared to other galaxies in the universe. The lightest galaxies are around a billion solar masses, while the heaviest are 30 trillion, or 30,000 times more massive.
Welcome to the night sky report for March 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. In March, the stars of spring lie eastward. Look for the constellations Gemini and Cancer to spot interesting celestial features like the Beehive Cluster. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the “normal” matter in the Universe. New results from NASA’s Chandra X-ray Observatory may have helped them locate this elusive expanse of missing matter. In the time between the first few minutes and the first billion years or so, much of the normal matter (meaning hydrogen, helium and other elements) made its way into cosmic dust, gas, and objects such as stars and planets that telescopes can see in the present day Universe. The problem is that when astronomers add up the mass of all the normal matter in the present day Universe, about a third of it can't be found. One idea is that the missing mass gathered into gigantic strands or filaments of “Warm” (temperature less than 100,000 Kelvin) and “Hot” (temperature greater than 100,000 Kelvin) gas in intergalactic space. These filaments are known by astronomers as the "Warm-Hot Intergalactic Medium" or WHIM. They are invisible to optical light telescopes, but some of the warm gas in filaments has been detected in ultraviolet light. Using a new technique, researchers have found new and strong evidence for the hot component of the WHIM based on data from Chandra and other telescopes. (Please note that the missing mass described here is distinct from the still mysterious dark matter).
Using data from NASA’s THEMIS mission, scientists have discovered ¬that when the Earth’s magnetopause is struck by a jet of plasma from the Sun, it vibrates like a drum, with waves echoing back and forth along its surface, much like they do on top of a drumhead. The new discovery comes several decades after such behavior was first theorized.
If extraterrestrial intelligence exists somewhere in our galaxy, a new MIT study proposes that laser technology on Earth could, in principle, be fashioned into something of a planetary porch light -- a beacon strong enough to attract attention from as far away as 20,000 light years. The findings suggest that if a high-powered 1 to 2 megawatt laser were focused through a massive 30 to 45 meter telescope and aimed out into space, the combination would produce a beam of infrared radiation strong enough to stand out from the sun’s energy. Such a signal could be detectable by alien astronomers performing a cursory survey of our section of the Milky Way -- especially if those astronomers live in nearby systems, such as around Proxima Centauri, the nearest star to Earth, or TRAPPIST-1, a star about 40 light years away that hosts seven exo-planets, three of which are potentially habitable.
Welcome to the night sky report for February 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. In February, the Winter Triangle is your guide to the night sky. The northern hemisphere is treated to views of the stars Procyon, Sirius, and Betelgeuse. Keep watching for the awe-inspiring views of the Orion Nebula, which is sculpted by the stellar winds of central bright stars. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
The strange orbits of some objects in the farthest reaches of our solar system, hypothesized by some astronomers to be perturbed by an unknown planet (Planet 9), can instead be explained by the combined gravitational force of small objects in the Kuiper Belt orbiting the Sun beyond Neptune. While the new theory is not the first to propose that the gravitational forces of a massive disc made of small objects could avoid the need for a ninth planet, it is the first such theory which is able to explain the significant features of the observed orbits while accounting for the mass and gravity of the other eight planets in our solar system.
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