See a Potentially Hazardous Asteroid From Your Backyard

Get ready for 2014 JO25, the biggest asteroid to fly this close to Earth since 2004. Good news — even a 3-inch telescope will show it!

Update: See below for a radar image and animation of 2014 JO25 captured by NASA's Goldstone Solar System Radar on April 18, 2017.
Just Saying Hello

An artist's view of an Earth-approaching asteroid passing close to our planet.
ESA / P.Carril

Every week, a handful of new Earth-approaching asteroids are caught in a net of robotic telescopes and join the ranks of nearly 16,000 other fly-by-night space boulders. Among their number is one 2014 JO25, discovered in May 2014 by astronomers at the Catalina Sky Survey (CSS) near Tucson, Arizona.

Observations made by NASA's NEOWISE mission have pegged the asteroid at roughly 650 meters (2,000 feet) across and twice as reflective as the Moon. That and its orbit are about all we know about this speeding space mountain for the moment.

That should change very soon. Asteroid 2014 JO25 will be making a close approach to Earth on April 19th. Because of its size and proximity, it will be bright enough to spot in a small, backyard telescope and moving fast enough to see in real time.

Over the Top of our Heads

Asteroid 2014 JO25, a relatively large Near Earth Asteroid (NEA) will pass 1.8 million kilometers (about 1.1 million miles) from Earth on Wednesday, April 19th. At a bit brighter than magnitude +11, it should be easy to see and track even in a 4-inch telescope. Click for an animation.
NASA / JPL with additions by the author

Closest approach occurs around 12 UT (7 a.m. CDT) April 19th when it zips by at 1.8 million km (fewer than 1.1 million miles) away, or about four times the distance to the Moon. When darkness falls in Europe and Africa that evening, the asteroid will shine at its peak magnitude of +10.7 along the Ursa Minor–Draco border. Several hours later, North American observers can catch it rolling west across Coma Berenices a hair fainter, between magnitude +10.8 and +11.0.

King to Queen in Two Nights

2014 JO25 travels swiftly from Cepheus to Virgo in just two days centered on its closest approach to Earth. Times are CDT.
Created with Chris Marriott's SkyMap

Small asteroids outnumber big ones by several orders of magnitude, making this pass of 2014 JO25 a must-see event. The last time an asteroid this size or larger blew by Earth was in September 2004, when 4179 Toutatis, a 5-km-tall bowling pin, came within about four lunar distances. Not until 2027 will we have another shot at seeing a big rock tumble by. That year, 800-meter-wide 1999 AN10 will cruise within one lunar distance of the hairs on your head.

Cruising Through Coma

In this closer view, tick marks show the asteroid's position every 15 minutes (with labels every hour) as it tracks across Coma Berenices on the night of April 19–20 CDT for observers in the Americas. Stars are shown to magnitude +11.5 and north is up.
Bob King; Source: Chris Marriott's SkyMap

Telescopes across the planet will be trained on 2014 JO25. Astronomers will seek to determine a rotation rate by watching as the asteroid's light varies in a regular way. Sometimes these variations are obvious visually at the telescope. Watch for changes in brightness as you follow 2014 JO25's progress across the sky. If it's spinning fast enough, you might even catch a couple rotations and see the light variations repeat.

One thing's for sure: During early evening hours on the 19th, the asteroid will cover ½° of sky in just under 30 minutes, or 1′ (arcminute) every minute. That's fast enough to see it creep across the field of view in real time.

Looks Like a Peanut

UPDATE April 19: This composite of 30 images of asteroid 2014 JO25 was generated with radar data collected using NASA's Goldstone Solar System Radar in California's Mojave Desert on Tuesday April 18. Click the image for a full-sized version. Click here to see the animation.

Reflectance spectroscopy, where astronomers use a spectrograph to examine how the asteroid absorbs sunlight depending upon the minerals that compose its regolith (soil), can reveal the object's surface composition. Radar observations are planned at NASA's Goldstone Radar in California between April 16–21 and at Arecibo Observatory in Puerto Rico April 12–21. Radar images will show the shape, allow determination of the rotation rate, and reveal surface details as small as a few meters (yards).

Hazardous to your health?

The April 19th encounter is the closest this asteroid has come to Earth for at least the last 400 years and will be its closest approach for at least the next 500 years. Although 2014 JO25 will fly safely past Earth, it's on the list of PHAs (Potentially Hazardous Asteroids), those rocks that are big enough and occasionally pass close enough to Earth to be of concern. PHAs have diameters of at least 100-150 meters (330-490 feet) and pass less than 0.05 a.u (7.5 million km / 4.6 million miles) from our planet. As of March 2017, we know of 1,786 of them. No known PHA is predicted to impact Earth for at least the next 100 years.

9–11:30 p.m. CDT path

This map (the first of three close-up maps, see below) shows the asteroid headed south-southwest across the constellation Coma Berenices during evening viewing hours for the Americas. Tick marks show its position every 15 minutes and stars are plotted to magnitude +11.5. Start time is 9 p.m. CDT (2 UT April 20). Click for a larger version you can print out and use at the telescope.
Bob King; Source: Chris Marriott's SkyMap

11 p.m.–2 a.m. path

Asteroid watchers and astrophotographers are in for a treat when 2014 JO25 passes just 15′ east of M64, the Black-Eye Galaxy, about 12:45 a.m. CDT on April 20th.
Bob King; Source: Chris Marriott's SkyMap

1–4 a.m. path

2014 JO25 fades to around magnitude +11.2–11.4 before dawn begins on April 20th.
Bob King; Source: Chris Marriott's SkyMap

2014 JO25 will makes its first appearance for most of us low in the northern sky in Cepheus during evening hours across the Americas on Tuesday, April 18th. At magnitude +13, it will be dim. Over the next 24 hours, this monster rock will sprint southwest across 80° of sky. Come nightfall on April 19th, it will be beautifully placed for viewing in Coma Berenices, a little brighter than magnitude +11, and quickly slowing down. The following evening, April 20th, the asteroid only gets as far as the Cup of Virgo, spinning away a few degrees north of Gamma (γ) Virginis at nightfall. It will be shining at magnitude +12 — still an easy find in a 6 or 8-inch telescope.

2014 JO25's European Jaunt

European observers can use this map, set for Paris, France. Times are local CEST (Central European Summer Time = UT+2) for April 19–20, as the asteroid passes through the constellation Canes Venatici. Stars are shown to magnitude +11.5. Bob King; Source: Chris Marriott's SkyMap

That gives us three nights of choice viewing. I've set the charts above for the central United States at latitude 40° N on the best night. As near-Earth asteroids go, 2014 JO25 isn't coming unusually close, so parallax (the apparent shift in the position of a nearby object against the sky background depending on your observing location) won't be objectionable. The asteroid's path will shift about 11′ over 90° of latitude (between 45° N and 45° S) or ~7″ (arcseconds) per degree of latitude. If you're south of 40° N, the path shifts slightly north; if you're north of 40 N°, the path shifts slightly south. Keep that in mind when using the charts.

Freestyle it

While the charts will work for most observers, you can always prepare your own. Here are two easy ways:

1. Download the free home planetarium software Stellarium for Windows or Mac. Once you've chosen your city, click on the configuration icon (lower left side of screen), select Plugins, scroll, and select Solar System Editor. Click Configure and select the Solar System tab. Select Import orbital elements in MPC format, then Asteroids. Under Select bookmark, choose the PHA option and click Get orbital elements. Scroll through the list and find 2014 JO25, then click Add to list. Next, close the dialog boxes, choose a time you want to view the asteroid, and click Search window (magnifying glass in lower-left corner of screen). Type in the name 2014 JO25 and the program will take you straight to it. I know — sounds like a lot of steps, but it's painless. And accurate.

2. If you already have a program like Starry Night, Megastar, etc. that can plot an asteroid path, just go to the Minor Planet and Comet Ephemeris Service, type 2014 JO25 in the open box, scroll to the end of the page, select your software. and click on the Generate ephemerides/HTML button. Save the file that pops up on your screen into your program, open the program, select the asteroid, and create a custom map with time intervals and a magnitude range to your liking.

In and Out in a Hurry

In this wider view, you can see the entire orbit of 2014 JO25 and the circumstances of its close encounter on April 19th.
Gianluca Masi

The key to spotting the asteroid is to allow time to identify and get familiar with the star field the asteroid will pass through 10 to 15 minutes in advance — then lay in wait for the moving object. Don't be surprised if 2014 JO25 deviates a little from the predicted path depending on parallax and late changes to its orbit, so keep watch not only on the path but around it, too.

You've got time to plan for the big night, so print out the maps and play with the software so you can be ready to board the asteroid express Wednesday evening. If bad weather intervenes, don't give up. Astrophysicist Gianluca Masi will share live, real-time images and commentary on his Virtual Telescope Project website beginning April 19th at 19:30 UT (2:30 p.m. CDT).

13 thoughts on “See a Potentially Hazardous Asteroid From Your Backyard

  1. StarChaser55StarChaser55

    Exciting and informative article; well done. Thanks for the section on how to create your own chart; definitely going to give that a try. As for Wednesday night, crossing my fingers – it looks like clear skies are forecast here in the Davis Mountains. Going to try to shoot a sequence of stills showing the asteroid’s movement – still testing my new iOptron SkyTracker Pro! Clear skies everyone!

  2. patrick-mortonpatrick-morton

    Hello and greetings from Club de astronomia Los Robles in Maracaibo,Venezuela !! thank you for such wonderfull article, !!its a wonderfull oportunity to watch an asteroid, were getting ready here, weather quite ok and holding !! thannk you best regards.Prf.Patrick and students from 14 schools.

  3. mpletcher6

    I live n central Florida. I have watch launches as long as I can remember. They can b seen from our front yard. I’ve gotten up m the middle of the night to video and take pictures of the last shuttle launch. I also had the fortune of being a guest of and having grandstand seats at one. I also was was at work and ran out to watch the horrible destruction and knew n that instant something was wrong and ran back n screaming turn on the T.V. something has happened. We r still watching launches and the humble on U tube. The Eclipse etc. I’m an amateur, but a researcher of knowledge and photographer. I’m now a full time caregiver to both my elderly parents so I have more time at home and want to learn more. My husband is a Math Professor and stats is one of his loves. Math n general. I have already given him a photo where they by the stars and Math etc show where the stars were the night we were Maried. I read about the astorid in USA Today and through links was lead to ur site.

  4. Martian-BachelorMartian-Bachelor

    > Type in the name 2015 JO25…
    Small typo there (2014).

    Charts are okay, but which program(s) generate(s) an ephemeris most painlessly?

    (BTW – “ephemeris” gets red-squiggly lined by the spell checker… ugh!
    They keep saying computers just keep getting smarter and smarter, so it must be the programmers who are getting dumber. lol – Second Law of Thermodynamics)

    It would be soooo kewl if one of these came really close, like close enough to scare the bejeezuz out of everyone! Better luck next time?

    1. Bob KingBob King Post author

      Thanks M.B. for pointing out the little typo – now corrected. Which program is most painless? Stellarium only produces one position at a time, not a path. As long as you use up-to-date ephemerides, lots of programs plot paths with next to no pain. Megastar and SkyMap are great, and I bet there are lots of others.

  5. StarChaser55StarChaser55

    Success! Shot 126 stills of 2014 JO25 using a Canon 80D and 200mm telephoto lens sitting on an iOptron SkyTracker Pro. Each exposure was 15 seconds long (f4.0, 1600 ISO), at 1 minute intervals over a two hour period starting at 9:36 PM CDT on the evening of April 19th. Posted the first three pics (first three minutes) in the S&T Gallery. Hoping to make an animated GIF movie from all of the pics. I noticed that the actual asteroid path differed from the finder chart path by about 7 minutes of arc; pretty close. Thanks again Bob for an excellent article – had fun doing this!

    1. Bob KingBob King Post author

      Happy to hear you had success, Starchaser and thanks for sharing your images in the gallery. Sadly, I was socked in with clouds, snow and rain but found a live feed and watched it online.

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