Dr. David Morrison: Near Earth Object Encounter Overview

At the time of closest approach, clouds are obscuring the sky in the vicinity of NASA Ames Research Center. We will therefore be unable to live stream the pass from Foothill College Observatory; however, we were able to capture video earlier in the day as the asteroid approached the Earth. You can see the asteroid here as it passes in front of the star cluster NGC 2439.


While the close distance to this asteroid will make it bright enough to be easily observed, that same distance can make it difficult to locate. There are several reasons behind this. It will be a moving target, moving at 2.5 degrees per hour near closest approach. That means you will have to know just where to look at just the right time. Many observers will use desktop planetarium program to do this. However, a number of these may not show the asteroid in its correct position. They may not carry the asteroid’s orbital elements to a high enough degree of precision. While such an error wouldn’t amount to much for an asteroid way out beyond the orbit of Mars, that error can translate to a big offset in the sky when looking at an asteroid this close. Also, many of these programs will not take into account changes in the asteroid’s orbit due to the gravitational tug it feels during its close approach to the Earth.

Perhaps the best way around this challenge is to generate a rough finder chart using your desktop planetarium software. Then use NASA’s JPL HORIZONS System (http://ssd.jpl.nasa.gov/horizons.cgi) to generate a precise ephemeris specific to your location. On the HORIZONS web interface, change the Target Body to 2004 BL86, and under Observer Location, enter your longitude and latitude or select a nearby city from the list. You can then select a range of times and a step size (time interval) for your list. Because the asteroid is moving so fast, choose a step size of one hour. The result will be a list of times and positions that you can then use to manually update your finder chart so that you can use it to see exactly when and where to look. The chart below was generated by Rick Baldridge of the Peninsula Astronomical Society for the Bay Area of Northern California, however it should be generally useful for wide-angle viewing by observers anywhere on Earth.

UPDATE: Due to local weather conditions at NASA Ames, we will not be streaming this asteroid pass. However, NASA’s Meteoroid Environment Office is planning to stream the pass from their observatory at Marshall Space Flight Center. Their stream can be accessed by clicking here.

This Near Earth Asteroid (NEA) pass will be streamed live! SSERVI is planning a webcast of asteroid 2004 BL86’s flyby at 8PM PDT on Monday, January 26 with a discussion by SSERVI senior scientist and renowned asteroid expert Dr. David Morrison. If the local weather is clear, SSERVI will follow Dr. Morrison’s presentation with a live stream of the asteroid pass from a video camera attached to an observatory telescope. Please check back on this page on Monday to catch the live stream.


An asteroid, designated 2004 BL86, will safely pass about three times the distance of Earth to the moon on January 26. From its reflected brightness, astronomers estimate that the asteroid is about a third of a mile (0.5 kilometers) in size. The flyby of 2004 BL86 will be the closest by any known space rock this large until asteroid 1999 AN10 flies past Earth in 2027.

At the time of its closest approach on January 26, the asteroid will be approximately 745,000 miles (1.2 million kilometers) from Earth.

“Monday, January 26 will be the closest asteroid 2004 BL86 will get to Earth for at least the next 200 years,” said Don Yeomans, who is retiring as manager of NASA’s Near Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, California, after 16 years in the position. “And while it poses no threat to Earth for the foreseeable future, it’s a relatively close approach by a relatively large asteroid, so it provides us a unique opportunity to observe and learn more.”

One way NASA scientists plan to learn more about 2004 BL86 is to observe it with microwaves (http://www.jpl.nasa.gov/news/news.php?release=2006-00a ). NASA’s Deep Space Network antenna at Goldstone, California, and the Arecibo Observatory in Puerto Rico will attempt to acquire science data and radar-generated images of the asteroid during the days surrounding its closest approach to Earth.

“When we get our radar data back the day after the flyby, we will have the first detailed images,” said radar astronomer Lance Benner of JPL, the principal investigator for the Goldstone radar observations of the asteroid. “At present, we know almost nothing about the asteroid, so there are bound to be surprises.”

Asteroid 2004 BL86 was initially discovered on Jan. 30, 2004 by a telescope of the Lincoln Near-Earth Asteroid Research (LINEAR) survey in White Sands, New Mexico.

The asteroid is expected to be observable to amateur astronomers with small telescopes and strong binoculars.

“I may grab my favorite binoculars and give it a shot myself,” said Yeomans. “Asteroids are something special. Not only did asteroids provide Earth with the building blocks of life and much of its water, but in the future, they will become valuable resources for mineral ores and other vital natural resources. They will also become the fueling stops for humanity as we continue to explore our solar system. There is something about asteroids that makes me want to look up.”

NASA’s Near-Earth Object Program Office is experiencing its first transition in leadership since it was formed almost 17 years ago. On Jan. 9, after a 39-year-long career at JPL, Yeomans retired. Paul Chodas, a long-time member of Yeomans’ team at JPL, has been designated as the new manager.

NASA detects, tracks and characterizes asteroids and comets using both ground- and space-based telescopes. Elements of the Near-Earth Object Program, often referred to as “Spaceguard,” discover these objects, characterize a subset of them and identify their close approaches to determine if any could be potentially hazardous to our planet.