суббота, 27 апреля 2019 г.

2019 April 27 The Galaxy, the Jet, and the Black Hole Image…


2019 April 27


The Galaxy, the Jet, and the Black Hole
Image Credit: NASA, JPL-Caltech, Event Horizon Telescope Collaboration


Explanation: Bright elliptical galaxy Messier 87 (M87) is home to the supermassive black hole captured by planet Earth’s Event Horizon Telescope in the first ever image of a black hole. Giant of the Virgo galaxy cluster about 55 million light-years away, M87 is the large galaxy rendered in blue hues in this infrared image from the Spitzer Space telescope. Though M87 appears mostly featureless and cloud-like, the Spitzer image does record details of relativistic jets blasting from the galaxy’s central region. Shown in the inset at top right, the jets themselves span thousands of light-years. The brighter jet seen on the right is approaching and close to our line of sight. Opposite, the shock created by the otherwise unseen receding jet lights up a fainter arc of material. Inset at bottom right, the historic black hole image is shown in context, at the center of giant galaxy and relativistic jets. Completely unresolved in the Spitzer image, the supermassive black hole surrounded by infalling material is the source of the enormous energy driving the relativistic jets from the center of active galaxy M87.


∞ Source: apod.nasa.gov/apod/ap190427.html


‘Old Sarum’ Earthworks and Iron Age Hillfort, Wiltshire, 21.4.19.

‘Old Sarum’ Earthworks and Iron Age Hillfort, Wiltshire, 21.4.19.












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High-Flying Spacecraft Finish 1000th Lap Around Earth!

The quadruplet spacecraft of the Magnetospheric Multiscale mission have just returned from their first adventure into the solar wind — sailing through the most intense winds of their journey so far.


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These spacecraft were designed to study Earth’s giant magnetic system, which shields our planet from the majority of the Sun’s constant outflow of material — what we call the solar wind.


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Usually, the Magnetospheric Multiscale spacecraft — MMS for short — take their measurements from inside Earth’s protective magnetic environment, the magnetosphere. But in February and March, the MMS spacecraft ventured beyond this magnetic barrier to measure that solar wind directly — a feat that meant they had to change up how they fly in a whole new way.


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Outside of Earth’s protective magnetic field, the spacecraft were completely immersed in the particles and magnetic fields of the solar wind. As they flew through the stream of material, the spacecraft traced out a wake behind each instrument, just like a boat in a river. To avoid measuring that wake, each spacecraft was tilted into the wind so the instruments could take clean measurements of the pristine solar wind, unaffected by the wake.


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Within the magnetosphere, the MMS spacecraft fly in a pyramid-shaped formation that allows them to study magnetic fields in 3D. But to study the solar wind, the mission team aligned spacecraft in a straight line at oddly spaced intervals. This string-of-pearls formation gave MMS a better look at how much the solar wind varies over different scales.


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Because the four spacecraft fly so close together, MMS relies on super-accurate navigation from GPS satellites. This venture into the solar wind took the spacecraft even farther from Earth than before, so MMS broke its own world record for highest-ever GPS fix. The spacecraft were over 116,000 miles above Earth — about halfway to the Moon — and still using GPS!


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Now, just in time for the 1,000th orbit of their mission — which adds up to 163 million miles flown! — the spacecraft are back in Earth’s magnetosphere, flying in their usual formation to study fundamental processes within our planet’s magnetic field.


Keep up with the latest MMS research at nasa.gov/mms, on Twitter @NASASun or with NASA Sun Science on Facebook.


Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


Meteor Activity Outlook for April 27-May 3 2019

Despite thin clouds and a bright moon, Nicolas Rossetto managed to capture this brilliant fireball shooting overhead on 15 April 2019 from Jouhe, France © Nicolas Rossetto  For more information on this fireball refer to https://fireball.amsmeteors.org/members/imo_view/event/2019/1771

May is the best springtime month (in the northern hemisphere) to view meteor activity. The eta Aquariids are very active the first two weeks of the month then fade as the month progresses. These meteors are only visible in the few dark hours prior to dawn. The remainder of the night has low meteor rates. The only other showers of note this month are the eta Lyrids and the Anthelion radiant. These will add only 2-3 meteors per hour to the total count. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the tropical southern latitudes (25 S) are strong and remain so the entire month.


During this period the moon wanes from nearly half-illuminated to almost new. This weekend the waning crescent moon rises during the early morning hours and will be a nuisance to meteor observers. It’s not overpowering like a full moon so by simply keeping the moon out of your field of view you can still view decent meteor activity during the morning hours. As the week progresses the slender moon will be a non-factor and one can view wherever they wish in the sky. The estimated total hourly meteor rates for evening observers this week is near 3 for those viewing from the northern hemisphere and 4 for those located south of the equator. For morning observers the estimated total hourly rates should be near 8 as seen from mid-northern latitudes (45N) and 13 as seen from tropical southern locations (25S). Morning rates are slightly reduced during this period due to lunar interference. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.


The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 27/28. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.





Radiant Positions at 20:00 LDST


Radiant Positions at 8:00pm Local Daylight Saving Time






Radiant Positions at 01:00 LDST


Radiant Positions at 1:00 Local Daylight Saving Time






Radiant Positions at 05:00 LDST


Radiant Positions at 5:00 Local Daylight Saving Time





These sources of meteoric activity are expected to be active this week.


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The last of the pi Puppids (PPU) are expected to be seen this week. The radiant is currently located at 07:32 (113) -46. This area of the sky is located in southern Puppis, 2 degrees south of the 3rd magnitude star known as sigma Puppis. This radiant is best placed as soon as it becomes dark when it lies highest above the horizon in a dark sky. Current rates are expected to be less than 1 per hour. Due to the southern location of this radiant, these meteors are not well seen from the northern hemisphere. With an entry velocity of 15 km/sec., the average meteor from this source would be of slow velocity.


The h Virginids (HVI) were discovered by Japanese observers of SonotaCo using video data obtained in 2007 and 2008. These meteors are active from April 20-May 4 with maximum activity occurring on the April 30th. At maximum, the radiant is located at 13:40 (205) -12. This area of the sky is located in southern Virgo, 2 degrees east of the 1st magnitude star known as Spica (alpha Virginis). This radiant is best placed near midnight local Daylight Saving (LDST), when it lies highest above the horizon in a dark sky. Current rates are expected to be less than 1 per hour even at maximum. These meteors are seen equally well from both hemispheres. With an entry velocity of 17 km/sec., the average meteor from this source would be of slow velocity.


The center of the large Anthelion (ANT) radiant is currently located at 15:20 (230) -18. This position lies in central Libra, 2 degrees northeast of the 5th magnitude star known as Iota1 Librae. Due to the large size of this radiant, Anthelion activity may also appear from easternmost Hydra as well as Libra. This radiant is best placed near 0200 LDST, when it lies on the meridian and is located highest in the sky. Rates at this time should be near 2 per hour as seen from mid-northern latitudes (45 N) and 3 per hour as seen from the southern tropics (S 25) . With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.


The last of the Lyrids (LYR) are expected to be seen this week. The radiant is currently located at 18:24 (276) +34. This area of the sky is located in western Lyra, 5 degrees southwest of the zero magnitude star known as Vega (alpha Lyrae). This radiant is best placed during the last hour before dawn when it lies highest above the horizon in a dark sky. Current rates are expected to be less than 1 per hour. Due to the northern location of this radiant, these meteors are not well seen from the southern hemisphere. With an entry velocity of 46 km/sec., the average meteor from this source would be of medium-swift velocity.


The April rho Cygnids (ARC) were discovered by Dr. Peter Brown during his meteoroid stream survey using the Canadian Meteor Orbit Radar. These meteors are active from April 26-May 4 with maximum activity occurring on the 28th. The radiant is currently located at 21:28 (322) +47. This area of the sky is located in eastern Cygnus some 10 degrees east of the 1st magnitude star known as Deneb (alpha Cygni). This radiant is best placed during the last hour before dawn when it lies highest above the horizon in a dark sky. Current rates are expected to be less than 1 per hour no matter your location. With an entry velocity of 41 km/sec., the average meteor from this source would be of medium velocity. Note that these meteors are synonymous with the Nu Cygnids (Molau and Rendtel, 2009).


The eta Aquariids (ETA) are particles from Halley’s Comet, produced in Earth-crossing orbits many centuries ago. We pass closest to these orbits from May 3 through the 11th. During this period the eta Aquariids are at their best, capable of producing zenith hourly rates (ZHRs) of 60. The actual visible rates are most often less than half this figure due to the low altitude of the radiant at dawn. Observed hourly rates at maximum normally vary from zero at 60 degrees north latitude to 30 near the equator and back down to near zero again in Antarctica, where the radiant elevation is again very low. Hourly rates this weekend will most likely be 1-2 per hour as seen from mid-northern latitudes. The radiant is currently located at 22:00 (330) -04. This area of the sky is located in northern Aquarius, 4 degrees south of the 3rd magnitude star known as Sadalmelik (alpha Aquarii). The best time to view this activity is during the hour before the start of morning twilight, when the radiant lies highest in a dark sky. With the radiant low in the east it would be best to face halfway up in the sky in that same direction. If the radiant has sufficient altitude eta Aquariid meteors can also be seen shooting down toward the eastern horizon. With an entry velocity of 66 kilometers per second, a majority of these meteors will appear to move swiftly with a high percentage of the bright meteors leaving persistent trains. Surprisingly, this shower produces very few fireballs.


As seen from the mid-northern hemisphere (45N) one would expect to see approximately 5 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 8 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.


The list below offers the information from above in tabular form. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.


 













































































SHOWER DATE OF MAXIMUM ACTIVITY CELESTIAL POSITION ENTRY VELOCITY CULMINATION HOURLY RATE CLASS
RA (RA in Deg.) DEC Km/Sec Local Daylight Saving Time North-South
pi Puppids (PPU) Apr 24 07:32 (113) -46 15 18:00 <1 – <1 III
h Virginids (HVI) Apr 30 13:40 (205) -12 17 00:00 <1 – <1 IV
Anthelions (ANT) 15:20 (230) -18 30 02:00 2 – 3 II
Lyrids (LYR) Apr 23 18:24 (276) +34 46 05:00 <1 – <1 I
April rho Cygnids (ARC) Apr 22 21:48 (327) +47 42 08:00 <1 – <1 IV
eta Aquariids (ETA) May 07 22:16 (334) -03 67 09:00 1 – 2 I

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Hubble Snaps a Crowded Cluster


NASA — Hubble Space Telescope (HST) patch.


April 26, 2019



This sparkling burst of stars is Messier 75. It is a globular cluster: a spherical collection of stars bound together by gravity. Clusters like this orbit around galaxies and typically reside in their outer and less-crowded areas, gathering to form dense communities in the galactic suburbs.


Messier 75 lies in our Milky Way galaxy in the constellation of Sagittarius (the Archer), around 67,000 light-years away from Earth. The majority of the cluster’s stars, about 400,000 in total, are found in its core; it is one of the most densely populated clusters ever found, with a phenomenal luminosity of some 180,000 times that of the Sun. No wonder it photographs so well!


Discovered in 1780 by Pierre Méchain, Messier 75 was also observed by Charles Messier and added to his catalog later that year. This image of Messier 75 was captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys.


Messier 75 is featured in Hubble’s Messier catalog, which includes some of the most fascinating objects that can be observed from Earth’s Northern Hemisphere. See the NASA-processed image and other Messier objects at: https://www.nasa.gov/content/goddard/hubble-s-messier-catalog.



Hubble Space Telescope (HST)

For more information about Hubble, visit:


http://hubblesite.org/


http://www.nasa.gov/hubble


http://www.spacetelescope.org/


Text Credits: ESA (European Space Agency)/NASA/Rob Garner/Image, Animation, Credits: ESA/Hubble & NASA, F. Ferraro et al.


Greetings, Orbiter.chArchive link


Crew Juggles Emergency Drill, Space Biology and Dragon Preps


ISS — Expedition 59 Mission patch.


April 26, 2019


The six-member Expedition 59 crew conducted a routine, periodic drill for response to emergencies today in the middle of a science-packed day. The astronauts also researched space biology while preparing for next week’s SpaceX Dragon cargo mission.


The space residents practiced communications, roles and responsibilities, and evacuating the station in the unlikely event of an emergency. The crew would split up, board their Soyuz spacecraft and undock quickly for a ride back to Earth. The two Soyuz crew ships docked to the International Space Station each hold three crewmembers.



Image above: NASA astronaut Christina Koch works on the COLBERT treadmill inside the Tranquility module. Image Credit: NASA.


NASA Flight Engineers Nick Hague and Anne McClain set up the ultrasound and optometry instruments today for more Fluid Shifts studies. Flight surgeons are exploring what happens to an astronaut’s veins and eyes due to the head-ward flow of fluids caused by microgravity.


Hague later checked out command and communications gear he and astronaut David Saint-Jacques will use when the SpaceX Dragon resupply ship arrives next week. Saint-Jacques will command the Canadarm2 robotic arm to capture Dragon early Friday, May 2, two days after it launches from Florida. Hague will monitor Dragon’s telemetry during its approach and rendezvous. NASA TV is broadcasting the pre-flight activities and mission events live.



International Space Station (ISS). Image Credit: NASA

Saint-Jacques and Flight Engineer Christina Koch also split the day feeding mice and cleaning cages for the Rodent Research-12 experiment. The study is investigating the immune system’s response to the conditions of long-term spaceflight.


Commander Oleg Kononenko focused much of his attention today on life support maintenance in the Russian segment of the orbital lab. Flight Engineer Alexey Ovchinin studied ways to maximize the effectiveness of exercise in the weightless environment of microgravity.


Related links:


Expedition 59: https://www.nasa.gov/mission_pages/station/expeditions/expedition59/index.html


SpaceX Dragon: https://www.nasa.gov/spacex


Canadarm2 robotic arm: https://www.nasa.gov/mission_pages/station/structure/elements/mobile-servicing-system.html


NASA TV: https://www.nasa.gov/nasatv


Rodent Research-12: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7868


Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html


International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html


Images (mentioned), Text, Credits: NASA/Mark Garcia.


Best regards, Orbiter.chArchive link


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