Originally posted by dollukka
reply to post by thehoneycomb
Big asteroid, potentially hazardous only 16,8 LD fly by. This might have some geological influence here.
(214869) 2007 PA8 was discovered by LINEAR on August 9, 2007.
Nothing is known about the physical properties of this object except its absolute magnitude of 16.2,
which suggests a diameter within a factor of two of about 1.8 km.
2007 PA8 will approach within 0.043 AU (17 lunar distances) on November 5, 2012, when it could be a
very strong radar target at Goldstone. We are planning an extensive campaign of Goldstone radar
observations and hope to use the chirp system to image this object.
With a Tisserand parameter of 2.944, the orbit of this asteroid resembles that of a Jupiter-family comet,
and given its comet-like orbit, we expect a low optical albedo on the order of ~5%.
When combined with its absolute magnitude, this corresponds to a diameter of ~3.5 km.
Consequently, 2007 PA8 could be one of the ten largest asteroids that has approached Earth this closely
in the past 100 years. Due to the strong SNRs and size of the object, we expect that radar imaging
will place hundreds or possibly thousands of pixels on this object at resolutions of 0.25 or 0.1 usec.
Fourteen tracks are scheduled at Goldstone between October 28-November 13, providing an outstanding
opportunity to study the physical properties of this object. View periods for 2007 PA8 also overlap
those scheduled for asteroid 1998 ST49 on October 16-19, and we plan to devote some of the time on those
dates to 2007 PA8 as well.
The closest approach occurs at declinations too far south for Arecibo to track.
2007 PA8 brightens below 15th magnitude at the end of September and it reaches a peak brightness at magnitude 11
just before the closest approach. It will be an excellent target for lightcurves and spectroscopy and it
will even be visible in small telescopes (8" and larger) for experienced observers.
We are expecting that lightcurves will become available in October, so it's possible that the
rotation period will be known before the observations begin. Preliminary results from Michael Hicks (JPL)
suggest that the period is roughly 15 hours.
2007 PA8 has been classified as a "Potentially Hazardous Asteroid" (PHA) by the IAU's Minor Planet Center.
Orbital and Physical Characteristics
orbit type Apollo
semimajor axis 2.827 AU
inclination 2 deg
perihelion distance 0.954 AU
aphelion distance 4.700 AU
absolute magnitude (H) 16.2
diameter ~3.5 km (assuming an optical albedo of 0.05)
rotation period ~15 h (M. D. Hicks, pers. comm.)
pole direction unknown
lightcurve amplitude unknown
spectral class unknown, likely optically dark
JPL/Horizons orbit diagram: ssd.jpl.nasa.gov...
Last update: 2012 October 18