Imagine a world without liquid water, just solid ice in all directions. It would certainly not be a place that most life forms would like to live. And yet our planet has gone through several frozen periods, in which a runaway climate effect led to global, or near global, ice cover. The last of these so-called "Snowball Earth" glaciations ended around 635 million years ago when complex life was just starting to develop. Early models showed that once ice reached tropical latitudes, a positive feedback loop would take hold, in which ice cover would lead to lower temperatures, which would add more ice cover, which would lower temperatures even more. This runaway effect would presumably continue until the entire planet froze over, with even the oceans covered with as much as a kilometer thick layer of ice. This so-called hard “Snowball Earth" would lock the planet into an eternal winter with no apparent way to escape from such a deep freeze. Indeed, scientists have had a hard time explaining how a hard snowball could ever thaw. One proposal is that volcanic activity releases greenhouse gases that eventually warm the planet back up. The amount of carbon dioxide (CO2) needed might be several hundred times higher than what our atmosphere contains now. The other method might be a giant asteroid strike, as is being proposed by Curtin University scientists in Australia.
A team of astronomers using NASA's Hubble Space Telescope has measured the Universe's expansion rate using a technique that is completely independent of any previous method. The results of the team, dubbed the H0LiCOW collaboration (as in “Holy Cow!”), further strengthens a troubling discrepancy between the expansion rate (the Hubble constant) calculated from measurements of the local Universe as compared to the rate predicted from background radiation in the early Universe, a time before galaxies and stars even existed. This latest value represents the most precise measurement yet using the gravitational lensing method, where the gravity of a foreground galaxy acts like a giant magnifying lens, amplifying and distorting light from background objects. This latest study did not rely on the traditional "cosmic distance ladder" technique to measure accurate distances to galaxies that use various types of stars as "milepost markers." Instead, the researchers employed the exotic physics of gravitational lensing to calculate the Universe's expansion rate. The new measurements vary significantly from the currently accepted values and something appears to be off.
Happy New Year and welcome to the night sky report for January 2020 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. The winter sky is filled with brilliant stars. In January, the northern hemisphere features beautiful views of Capella - a pair of giant yellow stars, Aldebaran - a red giant star, two star clusters - the Hyades (Caldwell 41) and the Pleiades (M45), and the Crab Nebula (M1). The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
Astronomers have spotted three giant black holes within a titanic collision of three galaxies. The unusual system was captured by several observatories, including three NASA space telescopes. It should be noted that five billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. As is the case with these three galaxies, this will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars. Most of the hundreds of billions of stars in each of the galaxies will never actually collide, but will pass rather freely between each other with little damage. This however, will not be the case for the interstellar matter consisting largely of clouds of debris, dust, and gas. The high relative velocities and pressures between the interacting interstellar clouds will pull, twist, and distort the individual galaxies and trigger a firestorm of star formation.
The Sun is revealing itself in dramatic detail and shedding light on how other stars may form and behave throughout the universe, all thanks to NASA's Parker Solar Probe. The spacecraft is enduring scorching temperatures to gather data, which is being shared for the first time in new studies that illuminate previously unknown and only theorized characteristics of our volatile celestial neighbor. The information Parker has uncovered about how the Sun constantly ejects material and energy will help scientists rewrite the models they use to understand and predict the space weather around our planet, and understand the process by which stars are created and evolve. During its initial flybys, Parker studied the Sun from a distance of about 15 million miles. That is already closer to the Sun than Mercury. But the spacecraft will get even closer in the future, as it travels at more than 213,000 mph -- faster than any previous spacecraft.
Welcome to the night sky report for December 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. Step outside on a cold December night when the stars shine bright to find the Big Dipper, Cassiopeia, and Cepheus. They will help you locate Eta Cassiopeiae (a binary star system), M103 (a fan-shaped open star cluster of about 170 stars), and Mu Cephei (a red giant variable star known as the Garnet Star). Also, look for beautiful pairings of Venus, Saturn, Mars, and the crescent Moon throughout the month, at sunrise and sunset. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
Gamma Ray Bursts (GRBs) were discovered by American surveillance satellites in the late 1960s. These satellites were looking for gamma rays coming from possible clandestine Soviet nuclear tests. Instead these satellites found brief but intense flashes of gamma rays coming from random directions in space. To this day GRBs remain one of the greatest mysteries of modern astronomy. Despite lasting only a few milliseconds to several minutes, they are the most energetic phenomena known. An individual GRB can release in a matter of seconds the same amount of energy that our Sun will radiate over its 10 billion year lifetime. These beams blast out of imploding stars at over 99 percent the speed of light. They carry most of their energy in the form of gamma rays -- a lethal form of radiation that can penetrate bone and tear apart living cells. If our planet got caught in a nearby Gamma Ray Burst, the atmosphere would be largely stripped away. The current record for a super powerful GRB has just occurred, and it goes to a January 2019 outburst. The eruption came from a galaxy located so far away that the explosion actually happened 5 billion years ago. When the radiation finally arrived at Earth, it was seen by our satellite sentries that monitor the sky for such fireworks, including NASA’s Swift and Fermi telescopes, in addition to the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes on the Canary Islands. Hubble can't detect gamma rays, but its sharp vision was used to see where the burst came from. Hubble found that the host galaxy of the GRB is actually one of a pair of colliding galaxies.
Largely unnoticed in the corners of countless classrooms around the world hangs the singular achievement of a Siberian-born scientist and the founding document of modern chemistry -- the periodic table of the elements, which turns 150 this year. While writing his textbook, Principles of Chemistry, Dmitri Mendeleev sought a logical way to organize all of the elements known to science at the time. Like many before him, Mendeleev noticed that certain elements resembled one another in their chemical properties. By ordering the elements by increasing atomic weight, he spotted a periodic repetition in these common properties and he published his periodic law and table-like list of elements in 1869. The periodic law allowed Mendeleev to predict the existence and properties of undiscovered elements that would ultimately fill the gaps in his table. Eventually, the discovery of protons and electrons changed the table in a subtle but important way. Mendeleev originally ordered his table by atomic weight, but the periodic table is now ordered by atomic number, which refers to the number of protons in the nucleus of an atom. The protons, in turn, define the number of electrons, located outside the nucleus, which control the properties that so regularly repeat within each column in the table.
Welcome to the night sky report for November 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. In November, hunt for the fainter constellations of fall, including Pisces, Aries, and Triangulum. They will guide you to find several galaxies, including the spiral galaxy M74 and M33 (the Triangulum Galaxy). On November 11 we're in for a rare treat, as the innermost planet, Mercury, passes directly in front of the Sun for a few hours. The event will last about five and a half hours, during which Mercury's path will take it right across the middle of the Sun's disk. The next Mercury transit that will be visible from North America isn't until 2049. (Warning: You should never look directly at the Sun without proper protection, as it can permanently damage your eyes). The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
Venus may have had a stable climate for billions of years. Now, a new study is uncovering the possibility that a global resurfacing event, probably linked to volcanic activity, may have transformed the planet from an Earth-like climate to the 462 degree hot-house that we see today. Earth and Venus seem completely different. Earth is a lush, clement world teeming with life, while Venus is hellish, with its surface roasting at temperatures higher than those of a kitchen oven. But underneath it all the two planets share a number of striking similarities. They are nearly identical in size. The basic composition of Venus and Earth is very similar. One difference stands out, however -- Venus has very little water. Were the contents of Earth's oceans to be spread evenly across our world, they would create a layer 3 km deep. If you were to condense the water vapor in Venus' atmosphere onto its surface, it would create a global puddle just 3 cm deep. Something catastrophic happened on Venus and what caused this is still a mystery.
Thirty years ago, on August 25, 1989, NASA's Voyager 2 spacecraft made a close flyby of Neptune, giving humanity its first close-up look at our Solar System's eighth planet and marking the end of the Voyager mission's Grand Tour of the Solar System's four giant planets - Jupiter, Saturn, Uranus, and Neptune. But that historic first was also a last -- No other spacecraft has visited Neptune since. Voyager 2 launched on August 20, 1977, about two weeks before its twin spacecraft, Voyager 1. The two spacecraft are today the most distant human-made objects, having recently passed through the Heliosphere – a giant bubble that surrounds the Solar System. The original goal of the two Voyager spacecraft was to just explore Jupiter and Saturn. However, as part of a mission extension, Voyager 2 also flew by Uranus in 1986 and Neptune in 1989, taking advantage of a once in a 176 year alignment of the planets that enabled it to take a grand tour of the outer planets. Today, Voyager 2 is about 18.2 billion kilometers, or 11.3 billion miles, from Earth. Voyager 1 is about 22.0 billion kilometers (13.7 billion miles) away from Earth. Judging by their unmatched track record, it seems likely that Voyager 2 and its twin, Voyager 1, will continue to be humanity's eyes and ears into the realm of the stars for years to come. As the Space Age hits the 62-year mark, there is little doubt -- The Voyagers are going the distance.
The demise of the dinosaurs is the world's ultimate who-dunit. Was it an asteroid impact? Volcanic eruptions? Climate change? Too many pesky mammals running around eating dino eggs? All of the above? None of the above? Two main camps exist in paleontology today, each having a different view of what killed the dinosaurs and other organisms at the time of the Cretaceous-Tertiary (KT) boundary: A large asteroid impact in the Yucatan Peninsula or volcanic eruptions worldwide, but predominantly in the Deccan Traps of India. Controversy has surrounded the topic for the last four decades and it has become difficult for the general public (and the scientific community at large) to understand the issue due to the tangled assemblage of data which seems to point in many different directions. Luckily, the controversy has not harmed the study of mass extinction causation, but rather has made it a more dynamic and interesting area of study. There has been no settlement to the issue so far, and no clear one is foreseeable. In general, it seems that many paleontologists lean towards the volcanic eruptions side, while many astronomers and physicists favor the asteroid impact side. Geologists are probably evenly split between the two. But recent evidence suggests that the answer may be a combination of the two theories, with the ultimate killer being global climate change triggered by the two events in tandem. It looks like the asteroid that killed off the dinosaurs probably rang the Earth like a bell, triggering super-volcanic eruptions around the globe that may have contributed to the devastation – A one-two punch that ultimately killed-off 75 percent of life on the planet.
Welcome to the night sky report for October 2019 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. Crisp, clear October nights are full of celestial showpieces. Find Pegasus, the flying horse of Greek myth, to pinpoint dense globular star clusters and galaxies, including our neighbor, the Andromeda Galaxy (M31, NGC224). Watch for views of M15 (NGC7078) and NGC7331. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
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