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AUGUST METEOR SHOWER
This is an early notice: the best showing of the 2018 Perseid meteors should be in the night between August 12 and 13 (Sunday-Monday), but you may already have a chance to see a few of them. They are members of a vast diffuse stream in space, millions of miles wide. That is why outliers can pass by Earth as early as the middle of July, and a few may continue till near the end of August. It is their peak, the densest part of the stream, through which we will pass in the night of August 12/13. The scene shown is in the earlier part of that night, and it’s not too different in earlier nights. But in no night are you really likely to see so many “shooting stars” simultaneously! Even in the core of the stream, the little bits of matter are thousands of miles apart. The radiant, or point from which the meteors in their parallel courses appear to streak, is at first over the northeastern horizon, then swings higher as the sky rotates, and is highest in the pre-dawn hours; and it’s then that more meteors are likely to be seen. The meteors (or meteoroids, as they are called when still out in space, before becoming visible by burning up in our atmosphere) are particles shed from Comet Swift-Tuttle, so they follow roughly in its orbit.
No matter where you live worldwide, the 2018 Perseid meteor shower will probably produce the greatest number of meteors on the mornings of August 11, 12 and 13. In a dark, moonless sky, this annual shower often produces 50 or more meteors per hour. And this year, in 2018, there will be no moonlight to ruin the show. It should be an awesome year to watch the Perseids! In the Northern Hemisphere, we rank the August Perseids as an all-time favorite meteor shower of every year. For us, this major shower takes place during the lazy, hazy days of summer, when many families are on vacation. And what could be more luxurious than taking a siesta in the heat of the day and watching this summertime classic in the relative coolness of night? People tend to focus on the peak mornings of the shower and that’s entirely appropriate. But meteors in annual showers – which come from streams of debris left behind in space by comets – typically last weeks, not days. Perseid meteors have been streaking across our skies since around July 17. We’ll see Perseids for 10 days or so after the peak mornings on August 11, 12 and 13. What’s more, the Perseids tend to build up gradually, yet fall off rapidly. So it’s often wise to watch in the couple of weeks prior to the peak … but not this year. We can’t start watching for Perseids in early August in 2018, because the moon is in the way.
It’s that magical time of year again, when the solar system’s favorite planet – Saturn – is well placed for viewing in our sky. Shining with a distinct golden color, Saturn is a lovely object to view with the eye alone. Binoculars will enhance its color … but to see Saturn’s rings you need a small telescope. And we do mean small. Veteran observer Alan MacRobert at SkyandTelescope.com has written: The rings of Saturn should be visible in even the smallest telescope at 25x [magnified by 25 times]. A good 3-inch scope at 50x [magnified by 50 times] can show them as a separate structure detached on all sides from the ball of the planet.
Space Weather News for May 25, 2018 http://spaceweather.com https://www.facebook.com/spaceweatherdotcom JELLYFISH SPRITES OVER OKLAHOMA: Last night in Oklahoma, a swarm of jellyfish sprites flashed above an intense thunderstorm approaching Oklahoma City. A photographer caught the display at nearly point-blank range, only ~80 miles away, which is unusually close for these forms of upward-directed lightning. Visit today's edition of Spaceweather.com to learn more about jellyfish sprites and why more of them may be in the offing. Remember, SpaceWeather.com is on Facebook!
Asteroid 2010 WC9 will safely pass at about half’s the moon’s distance on Tuesday, May 15, 2018. Estimates of its size range from 197 to 427 feet (60-130 meters), making the May 15 pass one of the closest approaches ever observed of an asteroid of this size. This asteroid was “lost” and then found again. The Catalina Sky Survey in Arizona first detected it on November 30, 2010, and astronomers watched it until December 1, when it became too faint to see. They didn’t have enough observations to track its orbit fully and so predict its return. On May 8, 2018 – almost eight years later – astronomers discovered an asteroid and gave it the temporary designation ZJ99C60. Then they realized it was asteroid 2010 WC9, returning. During the 2018 return, closest approach of asteroid 2010 WC9 will happen on May 15 at 22:05 UTC (6:05 pm EDT; translate to your time). At that time, the asteroid will be 0.53 lunar-distances from Earth (126,419 miles or 203,453 km from Earth). According to orbit calculations made by NASA’s Jet Propulsion Laboratory, the May 15 close approach is the closest of this particular asteroid in nearly 300 years. Is this a large asteroid? No, not by any absolute measure. But it is larger than the estimated size of the Chelyabinsk meteor, which entered Earth’s atmosphere, breaking windows in six Russian cities and causing some 1,500 people to seek medical attention, in 2013. Estimates of asteroid 2010 WC9’s diameter range from 197 to 427 feet (60-130 meters); estimates of the Chelyabinsk meteor’s size before encountering Earth’s atmosphere center around 65 feet (20 meters). Asteroid 2010 WC9 is an Apollo type space rock. At no time will it be visible to the eye as it sweeps past Earth. It might get as bright as magnitude +11, which would make it bright enough to be seen in amateur telescopes pointed at the correct location and time. Asteroid 2010 WC9 is travelling though space at a speed of 28,655 miles per hour (46,116 km/h). Asteroid 2010 WC9 at Minor Planet Center; at CNEOS Want to view the asteroid online? Guy Wells at Northolt Branch Observatories in London, England – which specializes in observations of near-Earth asteroids and other small solar system objects – emailed EarthSky on Friday to say: We are planning to broadcast this asteroid live to our Facebook page on the night of May 14, likely around midnight, if the weather forecast remains positive. The broadcast will be less than 25 minutes in duration, as the asteroid will cross our field of view within that period of time. The asteroid will be moving quite rapidly (30 arcseconds per minute). Our display will update every five seconds. We are of course collecting astrometric data whilst this is happening, but the motion of the asteroid will be apparent every five seconds! Daniel Bamberger, also at Northolt Branch Observatories, sent along the two images below. He wrote: We imaged this object twice: First on May 9, when it was still known by its temporary designation ZJ99C60; then again on May 10, after it was identified as asteroid 2010 WC9, which had been a lost asteroid for eight years. It is still a faint object of 18th magnitude, but it is brightening very rapidly: 2010 WC9 will be brighter than 11th magnitude at closest approach, making it visible in a small telescope!
A magnetosphere is that area of space, around a planet, that is controlled by the planet's magnetic field. The shape of the Earth's magnetosphere is the direct result of being blasted by solar wind. The solar wind compresses its sunward side to a distance of only 6 to 10 times the radius of the Earth. A supersonic shock wave is created sunward of Earth called the Bow Shock. Most of the solar wind particles are heated and slowed at the bow shock and detour around the Earth in the Magnetosheath. The solar wind drags out the night-side magnetosphere to possibly 1000 times Earth's radius; its exact length is not known. This extension of the magnetosphere is known as the Magnetotail. The outer boundary of Earth's confined geomagnetic field is called the Magnetopause. The Earth's magnetosphere is a highly dynamic structure that responds dramatically to solar variations. Credit: NASA/Goddard/Aaron Kaase
A camera mounted ahead caught this image of Starman, in Elon Musk’s red Tesla Roadster, as car and mannequin left Earth behind. Calculations by astronomers in the days after the launch suggest the payload reached a speed of 20.8 miles per second (33.5 km/sec) after the last burn, a faster speed than expected. Image via SpaceX. Last Tuesday (February 6, 2018), SpaceX’s Falcon Heavy successfully lifted off from Launch Complex 39A at Kennedy Space Center in Florida. Falcon Heavy is now the world’s most powerful operational rocket by a factor of two, providing a heavy-lift capability not seen since the Apollo era in the late 1960s and early ’70s, when mighty Saturn V rockets lifted astronauts to the moon. Falcon Heavy’s launch last Tuesday was a test flight, its maiden voyage, meant to prove the concept of the rocket itself (which is in essence three of SpaceX’s Falcon 9 rockets joined together). It definitely did! But SpaceX founder and CEO Elon Musk, as always, went further. He and his team placed Musk’s 2008 Tesla Roadster at the top of the rocket, with the goal of blasting it into an elliptical orbit between Earth and Mars. The orbit would, at times, bring the car – with its passenger, a mannequin nicknamed Starman, dressed for space – near Mars. The Falcon Heavy rocket test was a major success and a thrill for space fans. After livestreaming views from StarMan’s vantage point in Earth orbit SpaceX reignited the upper stage’s engine one last time, giving the Tesla a push beyond Earth’s orbit.
Humanity’s farthest and longest-lived spacecraft, Voyager 1 and 2, achieve 40 years of operation and exploration this August and September. Despite their vast distance, they continue to communicate with NASA daily, still probing the final frontier. Their story has not only impacted generations of current and future scientists and engineers, but also Earth’s culture, including film, art and music. Each spacecraft carries a Golden Record of Earth sounds, pictures and messages. Since the spacecraft could last billions of years, these circular time capsules could one day be the only traces of human civilization.
Mars seen by the Viking oriter. Image via NASA/JPL/USGS By Andrew Coates, UCL Europe has been trying to land on Mars since 2003, but none of the attempts have gone exactly according to plan. A couple of months ago, the ExoMars Schiaparelli landing demonstrator crashed onto the planet’s surface, losing contact with its mothership. However, the mission was partially successful, providing information that will enable Europe and Russia to land its ExoMars rover on the Red Planet in 2021. Now European research ministers have finally agreed to give the mission the outstanding €400m it needs to go ahead. A lot is at stake as the rover is poised to uniquely drill under the harsh Martian surface to search for signs of past, or even present, life. With the best of human endeavor, we must learn, try again and not give up. As leader of the international Panoramic Camera team on the rover, which will among other things provide surface geological and atmospheric context for the mission, I am one of many scientists working very hard to make it work. PanCam is one of nine state-of-the-art instruments which will help us analyze subsurface samples. The reason it is so hard to land on Mars is that the atmospheric pressure is low, less than 1% of Earth’s surface pressure. This means that any probe will descend very rapidly to the surface, and must be slowed. What’s more, the landing has to be done autonomously as the light travel time from Earth is three to 22 minutes. This delay transmission means we can’t steer the rapid process from Earth. NASA and Russia have had their own problems with landings in the past, before the spectacular successes with the US missions Viking, Pathfinder, Spirit,Opportunity, Phoenix and Curiosity
Our sun is located about two-thirds of the way out from the center of the Milky Way. Illustration via Caltech. The planets in our solar system orbit around the sun. One orbit of the Earth takes one year. Meanwhile, our entire solar system – our sun with its family of planets, moon, asteroid and comets – orbits the center of the Milky Way galaxy. Our sun and solar system move at about about 500,000 miles an hour (800,000 km/hr) in this huge orbit. So in 90 seconds, for example, we all move some 12,500 miles (20,000 km) in orbit around the galaxy’s center. Our Milky Way galaxy is a big place. Even at this blazing speed, it takes the sun approximately 225-250 million years to complete one journey around the galaxy’s center. This amount of time – the time it takes us to orbit the center of the galaxy – is sometimes called a cosmic year.
This artist’s concept puts solar system distances in perspective, but you have to think about it a bit to understand it. The scale bar is in astronomical units (AU), with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the sun to the Earth, by the way, which is about 93 million miles or 150 million kilometers. Neptune, the most distant planet from the sun, is about 30 AU. Informally, the term solar system is often used to mean the space surrounding our sun, out to the last planet. Astronomers, however, might speak of the solar system as the heliosphere, or sphere of the sun’s influence. Our dominates its own region of space and creates a sort of bubble of charged particles in the space surrounding it. These particles are “blown” out from the sun by the solar wind. It’s this heliosphere that Voyager 1 has now left. NASA says Voyager 1 actually crossed the heliopause, the boundary around the region of the sun’s influence, over a year ago, on August 25, 2012. It’s also possible, though, to picture the solar system as going out to the Oort Cloud, the source of the comets that swing by our sun on long time scales. Beyond the outer edge of the Oort Cloud, the sun’s gravitational influence begins to wane. The inner edge of the main part of the Oort Cloud could be as close as 1,000 AU from our sun. The outer edge is estimated to be around 100,000 AU. So that’s 100,000 times the Earth-sun distance.