There are currently about 1008 known PHAs.

There are about 5,955 known near earth asteroids

PHAs are Potentially Hazardous Asteroids - Data courtesy of NASA's Near Earth Object Observations Program

near earth objects

Confirmation of NEO 2008 EF9 on 2008 03 09

This NEO is traveling at a rate of 2,691 arc/sec. per hour.

NEO Follow-up Project - Overview

Students who participate in NASA's Near Earth Object Observations Program will receive acknowledgement by the Astronomical Research Institute for each NEO they report measurements on using data from the NEO Follow-up Project. You can find a table of NEO measurements made by students and school participation on this Website. The International Asteroid Search Campaign provides a vital role in helping students learn valuable techniques in NEO measurements. To see Virtual Impactor observations made by students, see this table. Virtual Impactors are of vital importance to NASA's mission to discover and measure all NEOs larger than 1km in diameter by the end of 2008.

So why study Near Earth Objects in the first place? Because there is a possible threat that the Earth could be struck by an asteroid. See this interesting link to NEO Apophis by The Planetary Society.

near earth objects

NASA Image

Potentially Hazardous Asteroids (PHAs) are currently defined based on parameters that measure the asteroid's potential to make threatening close approaches to the Earth. Specifically, all asteroids with an Earth Minimum Orbit Intersection Distance (MOID) of 0.05 AU or less and an absolute magnitude (H) of 22.0 or less are considered PHAs. In other words, asteroids that can't get any closer to the Earth (i.e. MOID) than 0.05 AU (roughly 7,480,000 km or 4,650,000 mi) or are smaller than about 150 m (500 ft) in diameter (i.e. H = 22.0 with assumed albedo of 13%) are not considered PHAs.

This "potential'' to make close Earth approaches does not mean a PHA will impact the Earth. It only means there is a possibility for such a threat. By monitoring these PHAs and updating their orbits as new observations become available, we can better predict the close-approach statistics and thus their Earth-impact threat.

The NEO Follow-Up Project involves conducting Near Earth Object Observations of new objects as they are discovered by the large survey telescopes such as LINEAR, the Catalina Sky Survey, LEONOS, SpaceWatch and others. This is a relatively easy project that takes a small amount of time to learn and students will see results very quickly.

NEO data on newly discovered objects is published at the Minor Planet Center (MPC) and on the NASA/JPL Horizons website. Our goal to make as many observations of these newly discovered objects as possible. Once all of these objects have been imaged, we will follow-up on other NEOs that have not been seen recently. The NEO Follow-up Project will attempt to recover NEOs that are listed on the MPC Bright Recovery Opportunities and Faint Recovery Opportunties. Some of these objects have not been seen for many years. Each month the Astronomical Research Institute provides the MPC with the positions on dozens of asteroids. This is real science and research for NASA's NEO Observations Program that can easily be accomplished by instructor and student researchers. This research along with student measures will make real contribution to science so the orbits of known Near Earth Objects will be better defined.

In the NEO Follow-Up Project, you will learn how to generate minor planet orbits and print out the expected coordinates of your target NEO. With powerful software you will be able to complete reports that will be sent to the Minor Planet Center enabling astronomers to refine orbital elements by fitting our observations to these known objects.

For complete details, software and manuals for conducting Near Earth Object Observations in your classroom, contact the Astronomical Research Institute. There is no cost to any students, teachers or schools for participation in this exciting research program.

Contributions of observations by the Astronomical Research Observatory are published in the IAU Electronic Circulars and in the Minor Planet Center's Electronic Circulars.

This project is funded by a NASA grant, NNX07AR16G.

Killer Asteroid Project

Back to Home Page