A CELESTIAL ONE-TWO PUNCH
....but No Knockout!
By P. Clay Sherrod, Arkansas Sky Observatories
**UPDATE APRIL 19!**
Close pass of asteroid 2014 JO25 from April 19, fog and heavy dew. Arkansas Sky Observatories 0.51m astrograph; 35-sec shots followed by 2-5 sec pause
ONLY TWO DAYS before the close pass of 2014 JO25. This will be worth getting up early for......nearly due north for northern latitudes high in the northeast skies around midnight, and almost at the North Celestial Pole (71 deg dec); by 4 a.m. CDT (09:00 UT). DIRECTION OF TRAVEL is slightly south of due west (to left in this photo)
From 21 astrometric measurements obtained at Arkansas Sky Observatories for April 19, the following orbital parameter is derived:
Orbital elements: 2014 JO25
Perihelion 2017 Mar 3.478629 14.3 TT = 11:29:13 (JD 2457815.978629)
Epoch 2017 Apr 19.0 TT = JDT 2457862.5 Earth MOID: 0.0090 Ve: 0.0361
M 33.23593 32 Me: 0.0277 Find_Orb
n 0.71442298 0.395 Peri. 49.56248 4.6
a 1.23926952 0.257 Node 30.87972 0.8
e 0.7569920 0.217 Incl. 17.91051 10
P 1.38/503.89d H 19.1 G 0.15 U 12.1
q 0.30115236 0.134 Q 2.17738668 0.73
From 21 observations. Arkansas Sky Observatories H45, 2017 Apr. 19 (34.5 min); mean residual 5".59
# State vector (heliocentric equatorial J2000):
# -0.874095808280 -0.448038509978 -0.182433407251 AU
# -6.538620306761 -14.346114334067 -10.249588358588 mAU/day
# MOIDs: Me 0.0277 Ve 0.0361 Ea 0.0090 Ma 0.1578
# MOIDs: Ju 3.2318 Sa 7.9488 Ur 16.9319 Ne 28.1829
# Elements written: 19 Apr 2017 13:21:17 (JD 2457863.056447)
# Full range of obs: 2017 Apr. 19 (34.5 min) (21 observations)
# Find_Orb ver: Jan 17 2017 13:36:17
# Perturbers: 00000408 (Sun/Earth/Moon); not using JPL DE
# Tisserand relative to Earth: 2.19124
# Earth encounter velocity 26.9793 km/s
# Barbee-style encounter velocity: 41.5751 km/s
# Diameter 638.4 meters (assuming 10% albedo)
# Score: 0.949067
Chart from ASO/GUIDE
Note from the star chart above the path of this 11th magnitude 1/3 mile rock as it passes rapidly to the lower right (SW), traveling a whopping 3.75 arc minute per minute of time (note the "X" mark one-minute time intervals. This telescopic graphic chart is showing the sky in RED and stars black; the field is about 1/2 degree across.....the white boxed area is a typical CCD frame that measures 11' x 22' arc in size. Limiting magnitude of stars shown is about 18th; north at TOP.
2014 JO25 will be circumpolar all night and this chart shows the star field (note that many 11th magnitude stars are in this field for comparison) through which the asteroid is passing for those short few minutes. Once found at 4:00 via this chart, keep moving your telescope slightly to the southwest to following this huge rock. During the time specified here, the asteroid is located in the constellation of DRACO. For those wishing to photograph this rare event, note that an exposure of about 0.5 second will be necessary to "freeze" the asteroid without much streaking due to motion; with CCD and at least an 8-inch telescope, this should easily suffice to capture both the asteroid and the stars shown in this field.
NOTE: If you do not catch this asteroid on April 18-19, the be sure and get out the EVENING of April 19-20, when the asteroid will be whizzing by through the constellation of Coma Berenices, transiting about midnight and at a brilliant MAGNITUDE 10.6 or so. Its motion will be very fast to the SW, but you can easily spot this as it moves across the star field or freeze it in your CCD in 1/10th sec or less.
April provides some celestial fireworks for sure with its more than a dozen annual meteor showers - notably the bright and spectacular "April Fireballs" - but for 2017 April presents us with a celestial showdown that is nearly unrivaled in terms of astronomical encounters with Earth.
In late April one of the largest asteroids to come close to Earth in modern times will pass nearly closer than any other yet seen, and the spectacularly bright and rich Comet C/2015 ER61 is going to swing at its closest pass by Earth and possible be visible to the naked eye.
The Huge Chunk of Space Rock: Asteroid 2014 JO25
The Near Earth Object (NEO) 2014 JO25 - a huge minor planet, or asteroid - is coming in at a high velocity clip and will pass incredibly close to Earth on April 19 at a rather frightening close pass of only 1.1 million miles, only about five times more distant than our own moon. Yet this asteroid is not moving in a predictable and synchronous motion relative to Earth - it is speeding through space at the time of the encounter at about 20 miles per second, covering more than 60 degrees of our sky in one night, making it very difficult for astronomers to track, even though it will be so bright as to be seen in a pair of large binoculars.
The asteroid will be overhead about midnight and moving rapidly to the southwest across our skies and poses absolutely no threat to the Earth - it will swing close, but definitely no chance of it impacting the Earth or influencing our safety in any way.
Asteroid Toutatis in 2004 - Image courtesy National Geographic
Discovered by Arizona astronomers in 2014, this huge space rock is one of the largest to pass this close to Earth - its diameter is suspected to be about 2,000 feet across, or almost a half-mile - quite large for an Earth-crossing asteroid. This is the closest that we have seen by such a large asteroid since Toutatis in 2004 which produced a close-brush passing only one million miles away. However, both of these may appears meager compared to the NEXT close pass by a minor planet of this size in 2027, when the more than half-mile-wide rock 1999 AN10 will definitely draw major attention passing less than ONE lunar distance (236,000 miles).
A Beautiful and Developing Comet C/2015 ER61
Comet C/2015 ER61 (PANSTARRS) is also approaching and will make its very close pass by Earth on the same night, April 19. Found from observatories in the mountains of Hawaii, this is becoming a spectacular sight, with a huge green coma, or head, and a very intricate gas tail; on April 19 this comet will be a very close 109 million miles distant, quite close from an astronomical standpoint and will be easily found rising in the southeastern skies about 3 a.m. and being high enough (about 15 degrees from the horizon) at dawn to be seen in binoculars in the constellation of Aquarius. The comet is moving quite rapidly to the northeast each morning, and thus will be moving closer into morning dawn and resulting in more difficulty seeing as May approaches.