Monthly Archives: May 2017

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 May 6

Explanation: Some 4 billion light-years away, massive galaxy cluster Abell 370 only appears to be dominated by two giant elliptical galaxies and infested with faint arcs in this sharp Hubble Space Telescope snapshot. The fainter, scattered bluish arcs along with the dramatic dragon arc below and left of center are images of galaxies that lie far beyond Abell 370. About twice as distant, their otherwise undetected light is magnified and distorted by the cluster's enormous gravitational mass, dominated by unseen dark matter. Providing a tantalizing glimpse of galaxies in the early universe, the effect is known as gravitational lensing. A consequence of warped spacetime it was first predicted by Einstein a century ago. Far beyond the spiky foreground Milky Way star at lower right, Abell 370 is seen toward the constellation Cetus, the Sea Monster. It is the last of six galaxy clusters imaged in the recently concluded Frontier Fields project.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) NASA Official: Phillip Newman Specific rights apply. NASA Web Privacy Policy and Important Notices A service of: ASD at NASA / GSFC & Michigan Tech. U.

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Astronomy Picture of the Day

Jupiter's position near Spica this year offers an excellent chance to see how planets got their Greek name asteres planetai, or "wandering stars." From February through May, Jupiter's regular eastward journey through the distant background stars is reversed by the parallax effect of Earth's faster motion. If you observe the planet every week or two, you'll see Jupiter moving away from Spica until June 10, then approaching it again until early September, after which it pulls away to the east. The SkySafari 5 app can display the path of a selected object.

Jupiter is perfectly positioned for observing this spring. As darkness falls the planet is already shining brightly in the southeastern evening sky. It crosses the sky over the course of the night and sets in the west just before dawn. And you don't have to wait for it to become fully dark before observing it the planet is bright enough to find in twilight. It's even possible to see Jupiter in broad daylight, if you know where to look.

At night, binoculars will reveal Jupiter's four largest moons waltzing around Jupiter on predictable schedules, sometimes gathering to one side or the other, and occasionally disappearing from view. A small telescope will show them more clearly, and also reveal the brown belts that make the planet look striped. A bigger telescope will let you see the Great Red Spot, a cyclonic storm that has raged for hundreds of years. When the geometry is just right, Jupiter's moons cast small black shadows while they cross the planet. You can see them, too, with a medium or large telescope.

In this edition of Mobile Astronomy, we'll tell you how to use apps to identify Jupiter, see the motions of its moons, find out when the Great Red Spot and moon shadows are visible, and even see Jupiter in the daytime! [Jupiter is a Feast for the Eyes In New Time-Lapse Animation (Video)]

In May 2017, Jupiter is sitting in the southeastern evening sky, within the constellation of Virgo. Virgo's brightest star, Spica, is about 10 degrees (an outstretched fist's diameter) below Jupiter. It's easy to tell the planet from the star. Despite Jupiter's great distance, its large globe reflects a lot of sunlight: it's second only to Venus in brightness among the planets, and it outshines every star in the night sky. By the time Jupiter sets in the west before dawn, the rotation of the sky has moved Spica upward to the left of the planet.

Jupiter will be visible in evenings for the next few months. But try to look now, while the planet is higher in the sky and shining through a thinner layer of the Earth's distorting atmosphere. By August, the planet will be sinking into the western twilight after sunset and shining through twice as much atmosphere. After mid-September, due to Earth's orbital motion, Jupiter will disappear from view while it's near the sun during solar conjuction, and then become a morning object at year-end.

Jupiter is spending this year's apparition amid the stars of Virgo, shining brightly in the southeastern sky as darkness falls, then crossing the sky to set in the west before dawn. The rotation of the night sky shifts the nearby bright star Spica from below the planet to its left. The moon passes Jupiter every month, close enough on occasion to allow finding the planet during the day.

The famous Great Red Spot (or GRS) on Jupiter is a cyclonic storm that has been raging on Jupiter for at least 185 years. A persistent spot on Jupiter was reported even earlier, by Giovanni Cassini, from 1665 to 1713 but no one is sure whether that was the same storm we see today. The Great Red Spot's oval is large enough to hold two to three, and it is visible in backyard telescopes. Jupiter rotates quite quickly once on its axis every 10 hours and the spot takes about 3 hours to traverse the planet's disk. Thus, the spot is not visible every night. A mobile astronomy app is a perfect way to find out when to see it.

Many sky-charting apps show Jupiter as a photographic image with the red spot visible, which might fool you into thinking it's always there. However, the better apps such as SkySafari 5 present Jupiter as a complete globe that rotates at the correct rate. If your app is set to the current time, it will show Jupiter as it appears in your telescope right now. But there's a catch. Jupiter is far enough away (more than 424 million miles, or 682 million kilometers) that we don't see events there in real time. The light needs time to travel all the way to Earth. It varies through the year, but right now, it's delayed by about 37 minutes. The SkySafari app has an algorithm that corrects for this, but some of the other sky-charting apps I tested did not.

In binoculars or a small telescope, Jupiter's four largest moons Io, Europa, Ganymede and Callisto become visible to either side of the planet. Their positions change nightly. A larger telescope will show the brown equatorial bands around the planet. And a good telescope will let you see the Great Red Spot. Jupiter's 10-hour rotation period causes the spot to be visible for only a few hours at a time, roughly every second evening. Use your astronomy app to find out when to look for it.

Another option is to choose an app that focuses exclusively on Jupiter. Sky & Telescope Magazine has a very good app for iOS users called JupiterMoons (developed by the SkySafari app team). It allows you to view the planet's current appearance and move forward and backward in time, in increments ranging from seconds to years. A separate page provides a list of upcoming GRS transits in local time, and another offers plenty of Jupiter facts and figures. The CalSKY website generates tables of GRS transits visible at your location, and plenty of additional information for Jupiter and the other planets.

Jupiter has more than 60 natural satellites, or moons many are small objects that have been trapped by the massive planet's gravity. The four largest moons were first observed by Galileo Galilei in 1609 using a very modest telescope. By observing the moons nightly over a period of weeks, he discovered that they were orbiting Jupiter a controversial statement in his day. Astronomers commonly refer to the big four as the Galilean moons. From closest to farthest from Jupiter, they are named Io, Europa, Ganymede and Callisto. Io is closest to its planet and moves faster than the outer ones, needing only 1.8 days to orbit Jupiter, while distant Callisto takes nearly 17 days. [Photos: The Galilean Moons of Jupiter]

Even modern-day binoculars are better than Galileo's little spyglass, so you can look for the moons yourself. Unlike the Earth's axis, which is tilted with respect to the plane of the solar system, Jupiter's axis is vertical, so the Galilean moons always appear along a straight line that runs parallel to the planet's equator. Their differing orbital speeds produce different arrangements of the moons: close together, well separated, arranged symmetrically and sometimes all clumped to the left or right (east or west) side of Jupiter. This makes it fun to check in on them from time to time. The Jupiter system runs like clockwork, so we can accurately predict events far into the future. Your app will tell you which ones are visible where you live.

It takes only a short while to notice the moons shifting in position. Your sky-charting app will have at least the four Galilean moons labeled, and perhaps some additional fainter ones. For iOS users, the Jupiter Guide app, the Gas Giants app and the Sky & Telescope app noted above all show a clear view of the arrangement of the planet and the moons, and offer a slider or buttons to alter the time. Android users should check out the Jupiter Simulator app. Unlike binoculars, most telescopes will invert or mirror image your view of Jupiter. Some of the apps allow you to select the mode that matches your equipment. Because the moons seldom line up symmetrically, it's simple to compare what you are observing in your eyepiece with the app, and configure the flip buttons until it's the same.

Our line of sight to Jupiter also means that the moons can transit (or cross) the planet; disappear or emerge from behind it (called occultations); or even pass in front of one another. Just as our moon is eclipsed when it passes through Earth's shadow, Jupiter's moons can blink off and on as they enter and depart its shadow. Depending on the geometry of Earth, Jupiter and the sun, the appearances and disappearances happen well away from the edge of Jupiter. They only take a few minutes, so they are great events to watch through a backyard telescope.

Jupiter and its moons present a number of interesting phenomena. Moons can darken or disappear from view as they enter the shadow of Jupiter or another moon, then reappear some time later. Moons can also pass in front of Jupiter, casting their shadows on the planet, or one another, making them appear to merge for a few minutes. Astronomy apps and online resources list the times of the events.

While the moons themselves are difficult to see while transiting Jupiter, their little round, black shadows are easy to see in a decent telescope. You just need to know when to look. The moons and their shadows take hours to cross Jupiter. Transits near Jupiter's equator last up to 3 hours, while high-latitude events are shorter. Use the app to find out the start and end time for each event. Remember that your telescope may flip or invert the view that the app shows. Other than SkySafari 5, most of the above apps will not show you the shadows on the planet, but if your app says that a moon is transiting, it's worth looking for a shadow. When planning to observe, you can run the time forward on the app to discover when the other types of events will be occurring. [Jupiter Quiz: Test Your Jovian Smarts]

If you tap the Info icon in SkySafari 5, it will present a list of upcoming Jupiter moon and Great Red Spot events, complete with quick links that show how they will look. Just tap the clock icon and then zoom the display to see Jupiter's disk and the moons.

On very special occasions, two or even three shadows can be transiting at the same time! These are worth setting the alarm for. On Thursday (May 11), starting at 9:59 p.m. EDT (0159 on May 12 GMT), Europa and Io will both have shadows on Jupiter for about 6 minutes. Europa's shadow will already be transiting as the sky darkens. And after the double-shadow event, Io's shadow will continue alone until midnight EDT.

On May 18, starting at 11:53 p.m. EDT (or 0353 on May 19 GMT), the shadows of Europa and Io cross again, this time for 49 minutes.

On May 26, at 1:47 a.m. EDT (0547 GMT), the same pair of shadows will cross for 72 minutes, but Jupiter will be very low in the western sky for observers in the Eastern time zone.

Jupiter's four Galilean moons frequently cast their dark round shadows on the planet. Your astronomy app or online resources can tell you when to look for them. On rare occasions two, or even three, shadows cross at the same time, such as this event on May 18. Europa's shadow (at right) will start to transit about 10:15 pm EDT. Io's shadow will join it for 47 minutes starting at 11:53 pm. Only a very large telescope will show the moons themselves.

There are online resources to track Jupiter phenomena, too. Los Angeles' Griffith Observatory provides a list of the Jupiter moon events on this page. The events and times are provided for the Pacific Time zone, but you can add or subtract the appropriate number of hours to correct for your own time zone. If you don't live in the Pacific Time zone, some of the events listed will not be visible for instance, if the sun has not yet set, or if Jupiter has already set where you live. Conversely, some additional events will be visible only in your time zone. (This is the advantage of using a mobile app tied to your location.)

Jupiter is easily bright enough to see in broad daylight, if you know where to look. Fortunately, the moon passes Jupiter every month, and often sits close enough to make spotting Jupiter fairly easy. To the naked eye, the planet is a bright pinprick of light, but binoculars or a telescope will reveal it as a small pale disk. This month it is rising at 5:30 p.m. local time, only 3 hours before sunset. But you can use the method I give below any time the planet is well separated from the sun. Make a point of trying it this summer and fall, when it's high in the sky during the afternoon. Remember: Never point binoculars or a telescope anywhere near the sun.

Below is a list of upcoming dates when the moon is close to Jupiter. Set your app to show the date indicated and center the view on the moon or Jupiter. Alter the time to see when they are close together, and also fairly high in the sky. Zoom in on the app's display so that the moon is large enough for you to estimate how many moon diameters apart they are. Finally, make note of what direction you will need to scan starting on the moon and moving toward Jupiter. Once you're outside, bring the moon into sharp focus in your binoculars, and then search in the correct direction, hopping by the number of moon diameters you noted. Try these dates:

Jupiter and Venus are both bright enough to see with naked eyes and binoculars in the daytime, if you know where to look. On May 7, the nearly full moon will pass only 1.75 degrees, or 3.5 moon diameters, from Jupiter. Focus your binoculars on the moon, and then scan to the right, counting moon diameters as you go. Once you see the planet, try to find its bright pinprick of light without the binoculars.

On May 7, the waxing full moon is about 3.5 moon diameters from Jupiter.

On June 3, the waxing gibbous moon is about 3 moon diameters from Jupiter.

On July 28, the waxing crescent moon is about 4 moon diameters from Jupiter.

On Dec. 14, the waning crescent moon is about 6 moon diameters from Jupiter.

When the moon isn't available, you can try enabling your device's gyro and compass sensors and use the app to show you where in the sky to scan for Jupiter. It's harder but doable. Venus is also observable using the same methods.

In future columns, we'll tour the southern skies not visible from the Northern Hemisphere, suggest some spring binocular objects, talk about galaxy types and more. Until next time keep looking up!

Editor's note: Chris Vaughan is an astronomy public outreach and education specialist, and operator of the historic 1.88 meter David Dunlap Observatory telescope. You can reach Chris Vaughan via email, and follow him on Twitter @astrogeoguy, as well as Facebook and Tumblr.

This article was provided by Simulation Curriculum, the leader in space science curriculum solutions and the makers of the SkySafari app for Android and iOS. Follow SkySafari on Twitter @SkySafariAstro. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

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How to See Jupiter by Day and its Moons by Night using Mobile Astronomy Apps - Space.com

Harold F. Weaver, a pioneering UC Berkeley astronomer whose discovery of radio emissions from molecules in outer space marked the new science of radio astronomy, has died at his East Bay home in Kensington. He was 99.

Nearly 60 years ago, Professor Weaver created the universitys first radio astronomy observatory at Hat Creek, a remote valley in Plumas County 290 miles from the Berkeley campus. The surrounding mountains shielded the observatory from interference by aircraft signals and the radio noises of civilization.

Its big receiver, a dish-shaped antenna, 85 feet in diameter, would lead to major discoveries and become the mainstay of the UC Radio Astronomy Laboratory, which Professor Weaver had founded on the Berkeley campus in 1958. He would direct it for the next 15 years.

At their Hat Creek observatory, Professor Weaver and his colleagues discovered the existence of astrophysical masers the equivalent in outer space of the lasers that had been created eight years earlier by UC Berkeleys Nobel laureate physicist Charles Townes. The masers were the first evidence that objects in the gas clouds of the galaxy were emitting coherent radiation.

Professor Weaver would later discover the first interstellar molecules known as hydroxyl radicals at a time when their mysterious radio emissions were often attributed to an unknown form of space matter named mysterium. Since his discovery, many other interstellar molecules have been detected in the atmosphere of comets.

His curiosity about the universe was wide: Even as a young astronomer on the Berkeley faculty in 1953 he was using galactic star clusters and Cepheid variable stars to calculate the outer limits of the Milky Way galaxy and to estimate that the universe was at least 3.6 billion years old close to todays estimates of 4 billion years.

Ten years later, he and the late Martin Schwartzchild of Princeton University launched a giant balloon from Palestine, Texas, in a project called Stratoscope. A 2-ton telescope carried by the balloon to an altitude of 15 miles peered at Mars and discovered the worlds first evidence of water vapor in the Martian atmosphere before it crashed in a mud-filled Louisiana cow pasture.

Harold Francis Weaver was born in San Jose in 1917, and by high school he was already building his own telescopes.

Still, he debated whether he would study classics or astronomy in college. The poet Robinson Jeffers had a telescope in his Carmel home, and encouraged the young man in his telescope-building interests.

As a UC Berkeley undergraduate in the astronomy department, he met his future wife, Cecile Trumpler, the daughter of astronomer Robert Julius Trumpler, and the two were married in 1939. It was Professor Trumpler who supervised his doctoral dissertation, and the two later collaborated on a book called Statistical Astronomy, which was published in 1953 and is still in use.

During World War II, he was conscripted to work on optics research for the National Defense Research Committee and later worked on isotope separation at what was then known as the Berkeley Radiation Lab.

After the war, he served as a staff scientist at Lick Observatory and joined the astronomy faculty at UC Berkeley in 1951. He retired as a professor in 1988 after publishing more than 70 professional papers and helping to guide development of the expanding Berkeley campus as a member and chairman of the Campus Facilities Committee in the 1950s and 1960s. He helped design the astronomy departments Campbell Hall, which was recently demolished and rebuilt on the same site.

Harold was truly a giant in our department of astronomy, UC astronomy Professor Alex Filippenko said after Professor Weavers April 26 death. I will always remember his warm smile, his generosity, and how he kept going with his research and other activities well into old age.

Professor Weaver had long served as treasurer both of the American Astronomical Society and Astronomical Society of the Pacific, and was a member of the group that founded the Chabot Space and Science Center in Oakland, where he served on the board of directors for many years.

He was also interested in contemporary writing, and for many years served as treasurer and a director of the Squaw Valley Community of Writers, a summer creative writing project located near Lake Tahoe.

The Weavers have donated their longtime Kensington home to UC to be used after their deaths to fund the Trumpler-Weaver Endowed Professorship in Astronomy at UC Berkeley.

Professor Weaver is survived by his wife and three children, Margot of Tucson, Paul of Kensington and Kirk of Houston.

Memorial gifts may be made to the Cal Alumni Leadership Award in care of the California Alumni Association, 1 Alumni House, Berkeley, CA 94720.

A memorial service is being arranged.

David Perlman is The San Francisco Chronicles science editor. Email: dperlman@sfchronicle.com

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Harold F. Weaver, pioneer of radio astronomy at UC Berkeley, dies - mySanAntonio.com

Yesterday, NASAs Cassini spacecraft entered its second of the 22 dives and scientists are excitedly waiting for the data to get a second look at the rings after the surprising information from the first dive: there appears to be no dust in the area.

With this revelation, the Cassini team is continuing on with their original plan for further observations. Though now the team can ignore their plan B and wont have to worry about dust affecting the instruments.

The region between the rings and Saturn is the big empty, apparently, Cassini Project Manager Earl Maize of NASAs Jet Propulsion Laboratory said in a press release. Cassini will stay the course, while the scientists work on the mystery of why the dust level is much lower than expected.

Having no other spacecraft pass through Saturns rings before, the team had prepared for a dusty environment in the 1,200-mile (2,000-kilometer-wide) area, planning to have Cassini use its round antenna as a shield.

When Cassinis Radio Plasma Wave Science (RPWS), the instruments in the shield that detect dust, detected a very small amount, scientists switched the data to audio format. Expecting to hear the pops and cracks of dust hitting the RPWS, the team was surprised to only hear the squeaks of Cassini diving through the rings.

It was a bit disorienting -- we werent hearing what we expected to hear, said William Kurth, RPWS team lead at the University of Iowa, Iowa City. Ive listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.

After assessing the data, the team believes Cassini only encountered a handful of dust particles no bigger than 1 micron across. Cassini is scheduled to reconnect today after its second dive yesterday.

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Cassini encounters the 'Big Empty' during its first dive - Astronomy Magazine