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NEO-Celestial Phenomenon: “It is said the comet always proceeds them.”

2017/04/09

INCREDIBLE COMET TAIL: More than 180 million km from Earth, something is happening to Comet PanSTARRS (C/2015 ER61). On April 4th and 5th, the comet brightened more than 6-fold, from magnitude +8.5 to +6.5, suddenly reaching the verge of naked-eye visibility despite its great distance from our planet. Now amateur astronomers are photographing an incredible tail. Gerald Rhemann sends this picture from his private observatory in Farm Tivoli, Namibia:

Comet PanSTARRS (C/2015 ER61)

Comet PanSTARRS (C/2015 ER61). Image: Gerald Rhemann from private observatory in Farm Tivoli, Namibia: via Spaceweather.com

“The comet’s tail is about 2.5 degrees long,” says Rhemann.

That means it spans more than 8 million km. For comparison, the entire sun is 1.4 million km wide; you could wrap the comet’s tail around the sun’s equator twice.  Another way of putting it: The distance from Earth to the Moon is only 5% of the length of the gaseous lane behind Comet PanSTARRS.

The comet’s outburst is probably caused by a fresh vein of icy material in the comet’s nucleus  exposing itself to solar radiation.  Furiously vaporizing, the comet’s core is spewing jets of dust and gas into space–a tail-building process that should intensify as the comet approaches the sun between now and early May.

The comet’s closest approach to Earth will be 176 million km (1.18 AU) on April 19th. Even at that distance, the comet might be a beautiful sight in backyard telescopes if current trends continue.

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On 09 April 2017, the the NASA all-sky camera network reported 10 fireballs.  (10 sporadics)
On 10 April 2017,  there were 1787  Potentially Hazardous Asteroids (PHAs).

Spaceweather.com

Related

Large asteroid coming close on April 19 (2017)

Asteroid 2014 JO25 will pass safely at 4.6 times the moon’s distance. It’s 60 times the diameter of the asteroid that penetrated the atmosphere over Chelyabinsk, Russia in 2013. People with small telescopes might be able to spot it.

A big asteroid will have a safely sweep past Earth on April 19, 2017. It’ll come so close – and it’s known so far in advance – that scientists will be able to study the space rock using both radar and optical observations. The flyby should also be visible in amateur telescopes. Asteroid 2014 JO25 was discovered by astronomers at the Catalina Sky Survey near Tucson, Arizona in May 2014. It appears to be roughly 2,000 feet (650 meters) in size, with a surface about twice as reflective as that of Earth’s moon. The asteroid will safely pass at some 1,098,733 miles (1,768,239 km ) from our planet or about 4.6 times the distance from Earth to the moon.

After analyzing the orbit of Asteroid 2014 JO25, astronomers have realized the April 19 encounter is the closest this asteroid has come to Earth for at least 400 years and will be its closest approach for at least the next 500 years. There is no danger as the space rock’s orbit is well known.

At 3:40 a.m. Central Time on April 19, asteroid 2014 JO25 will be located in front of the constellation Draco the Dragon, as seen here. Illustration by Eddie Irizarry using Stellarium.

A closer view of the space rock passing by the constellation Draco early on the morning April 19.

Observers using a computerized “Go To” telescope can point the instrument at star HIP 87728 a few minutes before 3:40 a.m. Central Time on April 19, and watch the asteroid passing by the magnitude 5 star in Draco. Illustration by Eddie Irizarry using Stellarium.

2014 JO25 is classified as a Potentially Hazardous Asteroid by the Minor Planet Center. The asteroid will sweep close enough to allow good radar observations. NASA has said they will study this asteroid using the Goldstone Radar in California from April 16 to 21. The Arecibo Observatory plans to do high resolution imaging using radar from April 15 to 20. Radar observations will provide a better understanding of the space rock’s size and shape.

Preliminary estimates indicate the asteroid’s size is about 60 times the diameter of the asteroid that penetrated the atmosphere over Chelyabinsk, Russia in February, 2013. NASA said:

There are no known future encounters by 2014 JO25 as close as the one in 2017 through 2500. It will be among the strongest asteroid radar targets of the year. The 2017 flyby is the closest by an asteroid at least this large since the encounter by 4179 Toutatis at four lunar distances in September 2004. The next known flyby by an object with a comparable or larger diameter will occur when 800-m-diameter asteroid 1999 AN10 approaches within one lunar distance in August 2027.

During the night of April 19, asteroid 2014 JO25 will pass though the constellations Canes Venatici and Coma Berenices. Illustration by Eddie Irizarry using Stellarium.

For backyard observers, the exciting news is that asteroid 2014 JO25 might be be visible moving across the stars though 8″-diameter and bigger telescopes. Can it be seen with smaller telescopes? Maybe, but in order to be able to detect its motion across the stars, at least an 8″ scope will be required. The asteroid will not be visible to the unaided eye, as it may show a brightness or magnitude between 10 and 11.

The asteroid is currently located in the direction of the sun, but – during the first hours of April 19 – the space rock will come into view for telescopes as it crosses the constellation of Draco. Then, during the night of April 19, asteroid 2014 JO25 will seem to move across the skies covering the distance equivalent to the moon’s diameter in about 18 minutes.

The asteroid will be close to star 41 Comae, which is very close to Beta Comae. This star is magnitude 4 and thus visible to the unaided eye. Illustration by Eddie Irizarry using Stellarium.

That’s fast enough for its motion to be detected though an amateur telescope. The best strategy to catch the space rock in your telescope is to observe a star known to be in the asteroid’s path, and wait for it.

If you are looking at the correct time and direction, the asteroid will appear as a very slowly moving “star.” Although its distance from us will make the space rock appear to move slowly, it is in fact traveling though space at a speed of 75,072 mph (120,816 km/h)!

Because it will appear to move very slowly, observers should take a good look at a reference star for a few minutes (not seconds) to detect the moving object.

Although asteroid 2014 JO25 will be closest to Earth on the morning of Wednesday, April 19, 2017, (around 7:24 a.m. Central Time / 12:24 UTC) the space rock may look a bit brighter (but still only visible in telescopes) during the night of April 19, because the asteroid will be at a higher elevation in our skies.

At around 9:30 p.m. Central Time on April 19, the space rock will be passing very close to 41 Comae Berenices (HIP 64022) a 4.8 magnitude star which is visible to the naked eye from suburban and dark skies. Illustration by Eddie Irizarry using Stellarium.

Will it be visible from both hemispheres? Yes. Observers in the Northern Hemisphere will be able to locate the asteroid both on the predawn hours and during the night of April 19. From South America, the space rock will only be visible during the night of April 19, at over 25 degrees above the northern horizon. Observers in Africa and Australia will also be able to spot the asteroid on April 19-20.

The asteroid’s nearness to Earth at the time of closest approach might cause a slight parallax effect. That means the space rock’s apparent nearness on our sky’s dome to a fixed star might differ slightly, as seen from different locations across Earth. Thus, if you don’t see the asteroid at the expected time, scan one more field of view up and down from your reference star, that is, the star you are waiting to see the asteroid to pass by.

By 10 p.m. Central Time, the asteroid will be passing close to star HIP 63891. At 11:40 p.m. Central Time (April 19) is passing by star HIP 63493. Illustration by Eddie Irizarry using Stellarium.

Bottom line: Asteroid 2014 JO25 will pass safely at 4.6 times the moon’s distance. People with small telescopes might be able to spot it. Charts here and other info on how to see it.

[Byline Eddie Irizarry]

08 April 2017
EarthSky.org

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See Also

NASA’s Hubble sees asteroid spout six comet-like tails
By in Science Wire | Space | Release Date: Nov 07, 2013

Source:

NASA’s Hubble Sees Asteroid Spouting Six Comet-Like Tails
NASA | RELEASE 13-321 | November 7, 2013
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