Ken Tapping, April 19, 2017
On 19 April an asteroid will pass close by. At its closest it will be less than five times the distance of the Moon. The asteroid, named 2014 JO25, is about 600 metres across. It will scoot across our northern sky in a few hours, moving at 33.5 km/s. It will be closest to us at 08:24 EDT, 05:24 PDT. However, to see it you’ll need a telescope.
If it were made of basalt, like the Moon, it would have a mass of some 300 million tonnes. This is the biggest object in about 13 years to pass this close. A rough estimate suggests on average we could be hit by something that size every million years or so. Such an event would certainly be a disaster, but it would not be likely to endanger our existence. Smaller objects pass within that distance every week and on average one of them could hit us every 80 years.
The Moon is peppered with craters due to impacts. The Earth has been hit at least as often, but weathering and the continuous recycling of the Earth’s surface due to subduction and the emergence of new land surface have erased most of them. However, there are still conspicuous craters on the Earth’s surface. These cosmic collisions are not unusual; they are just part of the ongoing process of planet building.
The Earth itself was formed through impacts, as dust and progressively larger lumps of material smashed together some 4.6 billion years ago. Some of that material contained ice, which brought us the water to make our oceans. Fortunately most of that primordial “building material” has been used, but there are still pieces of it orbiting the Sun. A piece of this material some 12km across smashed down in the Sudbury area in Ontario about 1.8 billion years ago. The geological disturbance brought a wealth of minerals closer to the surface and concentrated them.
One of the most well-known and dramatic impacts occurred about 64 million years ago. After 180 million years of stability, environmental change and habitat loss was putting many species, such as the dinosaurs and ammonites into a steady decline. Then a 10km diameter asteroid hit the Earth, leading to such a rapid environmental change that 75% of species became extinct, including the dinosaurs and ammonites. In 1908 something entered the atmosphere and exploded over Tunguska, Siberia. Over 2000 square kilometres were flattened, and glasses rattled on shelves in Paris, France. A tiny difference in arrival time could have put that impact in Europe.
Today, our species dominates the Earth. Feeding ourselves and providing for our other needs involves heavily exploiting our planet’s resources. That means we are becoming increasingly vulnerable to any sort of environmental disaster. Can we do anything to reduce the impact risk? This involves two problems: detecting impact threats and then somehow mitigating them.
Small, dark objects on a dark background are hard to see. We usually detect them just in time to watch them sail past. Current radar methods are no better. In principle we can use our observations to assess the possibilities of future collisions. This is rendered difficult by all our data being obtained over a tiny part of the orbit, and the perturbation of that orbit by little tugs by the other planets. This means that unless we can give threatening asteroids a really big “shove”, changing the orbit by more than the uncertainties in our calculations, we might turn a miss into a hit. Unfortunately, as yet we don’t know how to give objects with masses of millions of tonnes a big shove. Blowing them up, as in the movies, would just turn one threat into many. However, the detection and mitigation of cosmic impact threats are getting a lot of attention.
Ken Tapping is an astronomer at the Dominion Radio Astrophysical Observatory, Penticton, BC.
The college meteor camera is already seeing more bright meteors zipping overhead. The Perseid meteor shower started July 17, ends Aug 24 but peaks on Thursday night, August 11 and Friday morning Aug 12. If it’s cloudy Thursday, note that Wednesday night and Friday night will also be very active.
Meteor Flare Over Moon
This year the Earth will cross the centre of the comet debris; so we should get the full show. We should also get three additional early peaks: Jupiter’s gravity has shifted some debris; and we’ll see debris from the 1862 and 1479 comet ejection trails to hit this year. Peak estimates (by Esko Lyytinen and Mikhail Maslov) are 150 to 160 meteors per hour, about three per minute.
There are four peaks in two waves; we’ll miss the first wave since it hits Thursday in daylight; and the last wave which hits in Friday’s morning light. But the whole night should be pretty constant at 100 meteors/hour. Best seeing times in the East Kootenays would be after midnight once the Moon sets (low in Scorpius) and the skies darken; continuing until dawn at 5am. We’ll miss the last wave at 7am. But these peak times are estimates, we can hope they arrive during darkness instead.
(Mountain Daylight Savings Time-- minus 1 hr for Pacific) 1. Thurs Aug 11 at 4:34pm [1862 comet trail] 2. Aug 11 at 5:24pm [1479 comet trail] 3. Aug 11 from 6 to 10pm [Jupiter shifts] 4. Fri Aug 12 from 7 to 9am [Centre of comet orbit].
It takes the Earth a week to pass through all the ice and dust from comet Swift-Tuttle. The shower will gradually taper off and end by Aug 24. The meteors are travelling at a speed of 59 km/s when they enter the Earth’s atmosphere. Their trails will all point to Perseus (if it’s a Perseid). The closer they are, the smaller their trail: and the further away, the longer the trail. Look for their colours—at high speed they ionize the air to a green; then that fades to yellow, orange, red as it slows down. If they disrupt and flare, you may see green/bluish wide streaks that glow afterward for a second or two (mainly it’s water ice, but there may be metals present like copper or cobalt).
Where to look? The composite photo above shows the entire sky, and all the meteors that fell on 11 and 12 Aug 2015 over Cranbrook; taken by our college meteor camera. Perseus is the constellation to the North East (middle left side of the photo). Normally there are fewer meteors seen straight overhead, since there is less volume of atmosphere overhead. There are slightly more meteors seen high to the West around Hercules and above the handle of the big dipper; since the meteor trails are longer there, and the meteors skim lower in a greater volume of atmosphere. That’s where I aim my cameras. (Or where it’s darkest, away from the Moon or city streetlight glow).
Some of the meteors seen will be from the k-Cygnids running from August 6–19. These peak on August 18 at 3 meteors per hour. They show a number of slow falling fireballs moving at 25km/second.
This photo shows a k-Cygnid meteor crossing through Cygnus the Swan as seen during the last Perseid shower of 2015 (it’s tail is short and it points from Cygnus). Photo taken with a Nikon D100, Tamron 28mm f/2.5 lens, 30 second exposure. I outlined Cygnus in yellow against the Milky Way. The bright star Deneb is the tail at top, and Albireo is the beak at bottom. Photo credit: Rick Nowell.
While you’re out stargazing, here is a starmap showing the Perseus region of the sky, looking Northeast late after midnight in August. The Milky Way band (grey in the map) runs through Perseus; who is the Greek hero coming to rescue Andromeda (daughter of Cassiopeia) who is chained to the rocks. Look below the W of Cassiopeia (the Queen of Ethiopia). You should also see the great square of Pegasus, the winged horse to the right. If you have good eyes (or binoculars), you can spot the fuzzy cloud of the Andromeda Galaxy (M31 in the Map) just above Andromeda’s stick-figure knee. (Andromeda’s head is one corner of the square of Pegasus.) The big dipper, little dipper and Polaris are easy to locate to the left. (Starmap generated by Skyglobe software).
Note: to zoom in a picture or map and see the lines, right-click and open in new tab.
The best and most reliable meteor shower of the year are the Geminids at 120 meteors per hour on early Monday December 14. The second best are the Quadrantids at 120/hr on January 4 but these last only for a few hours. The Perseids are better known, since they occur on August 13 when it’s nice and warm out. But they’re actually number three on the list at 100 meteors per hour.
Since the new Moon occurs on Dec 11, the sky will be dark so we should see even the fainter meteors. The peak should occur around 10am in the morning, Dec 14, persisting for 24 hours. But 2am is fine when the shower’s radiant point, Gemini, rises high in the sky to the East. The meteors are the sand, dust and gravel remains of an Apollo asteroid (3200 Phaethon), coming in at medium speeds of 35km/second. (That’s a medium speed for a meteor. Other meteor shower velocities range from 11 to 72 km/s.) The Geminids come in various colours–65% being white, 26% yellow, and the remaining 9% blue, red and green. They’re active from Dec 4 until Thursday Dec 17. Last night I saw a bright yellow tinted fireball zip across Orion crossing a quarter of the Southern sky, leaving a shorter glowing trail along the last third of it’s flight; and another fireball went across Taurus just two minutes later. Last night I saw a bright yellow tinted fireball zip across Orion crossing a quarter of the Southern sky, leaving a shorter glowing trail along the last third of it’s flight; and another fireball went across Taurus just two minutes later.
Which direction is best to look? Where it’s darkest. As you can see in these composite photos from last year, the fireballs scatter all over the sky, radiating out from Gemini to the East. But when you watch the area around Gemini, the streaks there are shorter and slower moving. These fisheye photos show the whole sky as a circle: North is up, South down, East to the left, and West to right.
These photos were taken from Cranbrook, BC with the College of the Rockies meteor cam.
Below is a starmap looking East around 11pm on Dec 14. Note Gemini the Twins rising due East, just left of Orion the Hunter. Look for two bright stars, Castor over top of the other, Pollux. Gemini the Twins used to be a benevolent guide for the ancient Sailers. In movies you sometimes hear old sailors exclaim “By Jiminy!”. Sirius is the very bright star along the SouthEastern horizon below Orion. Taurus the Bull is the “>” shape above Orion, with the red eye of Aldebaran. The Pleiades are a small fuzzy patch above that.
These pictures are pixelated to fit in this small window–right click and open image in a new tab to zoom in more.
015-11-13 : 10:21 PST. Splashdown was last night at 22:19 PST in SRI LANKA off coast of Matara. Was late evening on USA Westcoast Thursday. Please enjoy my Blog. This is a conversation between young post-grad scientist Subath Amaradasa of the “Near Earth Objects” Team at the University of Ruhuna, who is on ground with French scientists from European Space Agency and William Smith who is the Hoyle-Shield coordinator at Cattle Point DARK SKY Urban Star Park, Victoria, Canada.
PS There will be a post script to the Snoopy event. Snoopy is almost certainly the Apollo 10 lunar lander – aka Snoopy. Its orbit which reaches way past the moon, makes this almost certain. No wonder it burned out. Very high speed entering the upper atmosphere. Ten times the speed of the fastest bullet on earth. Being small and with no shielding, no wonder it quickly burned out. Thanks to Rick Nowell for inspiring Subath Amaradasa and his “Near Earth Object” team at the University of Ruhuna in Matara, Sri Lanka.
(Email from Cattle Point Dark Sky Urban Star Park volunteer William Smith)
Dear Gerhard Drolshagen : On the Orbit of WT1190F (aka Snoopy)
Does object get captured weeks before and go into earth’s orbit, slowly losing speed and descending? OR does it come shooting directly into the earth’s atmosphere – almost perpendicular to a tangent ie pointing at the earth’s centre? This is important because if it orbits the earth one or two times as it slows down, then we might see it in the dark of the late evening where we are on West Coast of North America..
If you look at the ISS paths then focus in on the one which crosses southern India, this might indicate that SNOOPY (coming also NW-> SE) would pass over Panana, Bahamas, Northern Spain , Mediterranean and then IRAN . No luck for west coast of USA/Canada where I am.
Gerhard Drolshagen forwarded your message to me. Here is some of the info we have on WT1190F.
The object has been in Earth’s orbit at least since 2009. It has been moving in an elongated orbit with apogee at about twice the distance of the Moon, and perigee getting closer and closer to the Earth, until the upcoming re-entry. Since 2009, it has completed dozens of orbits around the Earth, and each orbit is about a month long.
The impact trajectory is not very vertical, but still much steeper than the typical re-entry of a low-orbiting satellite. It will come in with an angle of about 20° from the horizontal (=70° from vertical).
Given the fact that the orbit is so long, the geometry is totally different from a pass of the ISS. The latter orbits the Earth in about 90 minutes, while WT1190F takes weeks. So the current pass is actually the last part of the last orbit for this object.
Anyway, from a geometry point of view, it will definitely be observable from north America in the morning hours of November 12. However, it will be very faint, magnitude 19 or so, invisible by eye even with a large telescope. A CCD camera and at least a moderate-size telescope will be needed to get an image of it at that time.
Even for Europe and Northern Africa, which are the countries best-placed to observe it just hours before impact, it will only reach magnitude 15 or so, too faint for anything but images with a good telescope.
If you want to get an ephemeris for a specific site, I suggest you use this page from the Minor Planet Center:http://www.minorplanetcenter.net/iau/artsats/artsats.html. Just select WT1190F, enter the required information, and you will get your specific ephemeris based on the latest data.
Let us know if you need any additional info, and thanks for contacting us.
PS Young post-grads : http://hoyleshield.wesmith104.com/?page_id=80
> Object 2015 VO105 is of interest to NASA. Any and all information on
> this target would be most appreciated.
CON D. J. Tholen
OBS Y. Ramanjooloo, D. Hung
MEA D. J. Tholen
TEL 2.24-m University of Hawaii reflector NET PPMXL ACK 2015 VO105
K15VA5O C2015 11 17.23158323 38 55.363+13 34 14.08 19.3 R 568
K15VA5O C2015 11 17.23227823 38 55.804+13 34 12.10 19.3 R 568
Epoch 2016 Jan 13.0 TT = JDT 2457400.5 Tholen
M 124.69083 (2000.0) P Q
n 0.92262164 Peri. 84.14714 +0.82467835 +0.56135157
a 1.0450096 Node 241.68431 -0.54505393 +0.75606295
e 0.1214306 Incl. 4.50906 -0.15106895 +0.33653116
P 1.07 H 24.0 G 0.15
Residuals in seconds of arc
151112 G45 0.25+ 0.21+ 151113 926 0.10+ 0.04+ 151114 H01 0.18+ 0.40-
151112 G45 0.01+ 0.09+ 151113 926 0.09+ 0.15+ 151114 H01 0.26+ 0.32-
151112 G45 0.14- 0.45- 151113 C77 (0.50+ 0.80-) 151114 291 0.31- 0.24+
151112 G45 0.13+ 0.27+ 151113 C77 (0.65+ 1.48-) 151114 291 0.32- 0.19+
151112 G45 0.24+ 0.11+ 151113 C77 0.41+ 0.33- 151114 H01 0.20+ 0.37-
151113 291 0.51- 0.27+ 151114 926 0.25+ 0.38- 151114 291 0.34- 0.13+
151113 291 0.12- 0.23+ 151114 926 0.23- 0.17- 151117 568 0.01+ 0.01+
151113 291 0.40- 0.26+ 151114 926 0.05+ 0.21- 151117 568 0.01- 0.01-
151113 926 0.19- 0.22+ 151114 H01 0.33+ 0.31-
Paul Abell firstname.lastname@example.org
On the Hunt for rare rock after meteorite falls in December
University of Calgary geoscience professor asking for the public’s help.
A month after a spectacular fireball December 20, 2014, over the Rocky Mountains, University of Calgary researcher Alan Hildebrand is on a quest for rare meteorites.
In the early morning hours of December 20 a small piece of an asteroid entered Earth’s atmosphere high above Canal Flats, British Columbia, headed northeastwards towards Calgary, Alberta. Although western B.C. and eastern Alberta were overcast, the fireball was seen and imaged over the region between the clouds in both provinces. One spectacular still image was luckily taken by Brett Abernethy who was out with a friend imaging the night sky over Mt. Rundle near Banff when the fireball blazed an 80 km-long trail across the sky (See attached figure 1). Brett says, “We were looking north when everything lit up and we turned to see the fireball. It broke into at least three pieces and turned bright orange before fading away. After the initial shock I remembered that I was exposing a shot during the fireball and was overjoyed to discover that the shot was not overexposed.” Brett alerted the Calgary Herald to the event, who published his image which stimulated on-line discussion from other eyewitnesses.
In his search for more information about the fireball Hildebrand contacted Rick Nowell at the College of the Rockies in Cranbrook, B.C., who recorded it with his Sandia all-sky video camera through patchy clouds, and was able to correctly mark the fireball’s start time to precisely 00:25:00. With this accurate time, another all-sky still image was obtained from the University of Calgary’s Rothney Astrophysical Observatory (RAO). With these additional images in hand, he and his team were able to triangulate its location in the sky.
“It was very interesting to see how precisely a fireball path could be located just from two pictures taken more than 100 km away. We probably know where it was, start to finish within 100 metres,” says Lincoln Hanton, a recent University of Calgary graduate working with Hildebrand. The video recorded in Cranbrook and the fireball’s trajectory also show that it was a relatively slow entry velocity which favours the fall of meteorites.
Hildebrand says the fireball shows extraordinary properties. “In the photo taken by Brett, the fireball becomes visible at approximately 100 km altitude, starts fragmenting at approximately 60 km, and has its last and biggest explosion at 43 km. Those altitudes are much higher than normal. That means the rock was likely a weak type of asteroid.”
Rare carbonaceous chondrite rock
Hildebrand says the apparent weakness displayed indicates that this rock was unusual, probably a carbonaceous chondrite, which is a specific type of stony meteorite that originates from the Outer Asteroid Belt. At that distance from the Sun water and carbon-bearing compounds condensed and mixed into asteroidal bodies. Carbonaceous chondrites represent only approximately three per cent of meteorites that fall on Earth.
“Eyewitness accounts indicate that meteorites fell after surviving the trip through the atmosphere; the estimated rock mass entering the atmosphere was about 100 kg, but the largest pieces on the ground are probably only 2 kg,” says Hildebrand. “The meteorites fell in a forested area of the upper White River valley. It’s a tough area to search.” (See Figure 2)
Hildebrand says with the possibility of such a rare find his team will do some searching in the spring and encourage any others who can travel safely in this relatively remote area to search as well. How you can help
Hildebrand and his team are eager to talk with anyone who saw the fireball from Canal Flats, Fairmont Hot Springs, or Elkford, B.C. He encourages property owners in that region to check security camera systems for any shadows cast by the fireball. Anyone who had a wildlife camera in the region is also asked to check that date and time for moving shadows. Contact the University of Calgary at 403-220-8969 or via email at email@example.com.
Contact information: Brett Abernethy 403-620-6929 Lincoln Hanton 403-220-8969 Alan Hildebrand 403-220-2291 Rick Nowell 250-489-2751 ext 3585
Figure 1: Brett Abernethy’s image of the Dec 20 fireball looking south over Mt. Rundle from near Johnson Lake. The fireball crossed the constellation of Orion and then began fragmenting where the trail brightens and broadens. Note the slight reddening at the fireball’s end as the surviving rock fragments slowed and cooled before falling to the ground. Image is a 40 second exposure taken with a Canon 5D Mark III with a wide angle Zeiss 21 mm lens which slightly compresses the vertical aspect of the image. (All rights reserved)
Figure 2: Satellite image of eastern British Columbia showing location of the fireball trajectory projected onto the ground and estimated meteorite fall area as a yellow ellipse. The end of the fireball was about 40 km east of Fairmont Hot Springs. An eyewitness in Canal Flats would have seen the fireball travel almost straight downwards in the sky. (Figure constructed on Google Earth base)
One of the best meteor showers during the year are the Geminids, which occur annually on Dec 14. Earth enters the fringes of their orbit from Dec 4 until Dec 17. The peak of 120 meteors per hour, should be from Saturday noon Dec 13, until Sunday morning 10am Dec 14, 2014.
The skies were dark, since the Moon didn’t rise until after midnight. Although both nights it got cloudy around 1am where I am near Cranbrook, BC. The meteors were generally bright, medium fast speeds of 35km/s, and different colours. I saw white and red. This shower has some mass sorting, with small dust arriving the first day, followed by grains of sand, then pebbles a day later. It’s debris from a 5km diameter asteroid, 3200 Pheathon.
Dec 16 is also the peak for a smaller meteor shower, the Coma Berenicids, with a peak of 3 meteors per hour.
I took three Nikon cameras out. I goofed on one camera, I had it set for just ISO 1000. That captured two meteors in Ursa Minor, and that’s why they were so dim. The other two cameras were set at 3200 ISO, which is optimum. The max is 6400, but that can be snowy. The slight background brown glow is woodsmoke and thin cloud, the camera sensor shows haze like that. This was a Vivitar 28mm f/2.5 lens, hooded against the frost. All the tripods and camera equipment quickly frosted over at the -7 deg temperatures.
I was out again Sunday evening by Horseshoe Lake, with clouds over Orion. I got a hundred more photos and listened to coyotes howling nearby. The meteors were pretty nice still, I saw one every minute, some just out of the corners of my eye. Most were white falling parallel to the northern and southern horizon. Two I saw were moving slow, red in colour, on the far Western horizon.