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Astronomers have known since 1957 that the Milky Way’s disc – where most of its hundreds of billions of stars reside – is not flat but somewhat curved upwards on one side and downwards on the other. For years, they debated what is causing this warp. They have proposed various theories including the influence of nearby galaxies or the effects of an imaginary dark matter halo. With its unique survey of more than one billion stars in our galaxy, ESA’s star-mapping satellite Gaia might hold the key to solving this mystery. A team of scientists using data from the second Gaia data release has now confirmed previous hints that this warp is not static but changes its orientation over time. Astronomers call this phenomenon precession and it could be compared to the wobble of a spinning top as its axis rotates.

Welcome to the night sky report for March 2020 -- 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 star cluster M35, the Beehive Cluster, and NGC 3923, an oblong elliptical galaxy with an interesting ripple pattern. If you're up early any morning during March, you'll want to go out and look toward the east to catch a lovely grouping of Mars, Jupiter, and Saturn. The three planets are visible before dawn throughout the month.

Ninety years ago this month, Clyde Tombaugh, a young astronomer working at Lowell Observatory in Flagstaff, Arizona, discovered Pluto. In doing so he unknowingly opened the door to the vast "third zone" of the solar system we now know as the Kuiper Belt, containing countless planetesimals and dwarf planets—the third class of planets in our solar system.

Astronomers from UCLA’s Galactic Center Orbits Initiative have discovered a new class of bizarre objects (dubbed G-Objects) at the center of our galaxy, not far from the supermassive black hole called Sagittarius A. These objects look like gas and behave like stars. They are compact most of the time (like stars) and stretch out (like gas) when their orbits bring them closest to the black hole.

In astrophysics, gamma rays are known to be produced by some of the most energetic objects in the universe: supernova explosions, pulsars, neutron stars, and the swirling environments around black holes. When the highly energetic gamma rays reach Earth, they interact with molecules high in the Earth’s atmosphere and create a fleeting pulse of Cherenkov light in an air shower. The burst of light particles or photons lasts less than the blink of an eye -- on the order of six nanoseconds. Each pulse enables detection of a gamma ray a trillion times more energetic than can be observed with the human eye. A new type of telescope, known formally as the Schwarzchild-Couder Telescope, has been deployed as a high-end test bed for technologies that will be used in the Cherenkov Telescope Array (CTA) -- a configuration of approximately 100 telescopes to be situated in the Canary Islands and Chile, intended to give astrophysicists their best look ever at the transient effects of gamma rays interacting with particles high in the Earth’s atmosphere.

Welcome to the night sky report for February 2020 -- 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. Look for 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.

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.