Download Looking at our Neighbors with the VLA

Planetary Radio
Astronomy
Bryan Butler
What kinds of things do we
observe with the VLA?
45% - Extragalactic
20% - Galactic
30% - Stellar
5% - Solar system
Solar System “Bodies”
Sun
 IPM
 Giant planets
 Terrestrial planets
 Moons
 Small bodies

Planetary Radio Astronomy
Observation of radio wavelength radiation which has
interacted with a solar system body in any way, and use of
the data to deduce information about the body:
 spin/orbit state
 surface and subsurface properties
 atmospheric properties
 magnetospheric properties
 ring properties
Types of radiation:
 thermal emission
 reflected emission (radar or other)
 synchrotron emission
 occultations
Mercury

Closest to Sun

Magnetic field

No atmosphere

Hot!
Mercury - Thermal Emission
Mitchell & de Pater 1994
The Goldstone/VLA
Radar
Mercury - Radar
Butler et al. 1993
polar ice?
Volcanoes?
Venus

Closest to Earth

Thick atmosphere

Hot!
Venus - models
Venus models at C, X, U, and K-bands:
Venus - residuals
Venus residual images at U and K-bands:
Venus – Thermal Emission
Examination of the brightness temperature
spectrum of Venus shows unexpected
behavior at long wavelengths:
Moon – scaled & offset
Mars

Most like Earth

Thin atmosphere

Cold

Interesting Geology
Mars - Atmospheric Water
Clancy, Grossman, & Muhleman 1992
cold & dry!
Mars - Radar
Butler, Muhleman & Slade 1994
polar cap
lava flows
“Stealth”
Jupiter

Biggest planet

Gas ball

“weather” (GRS)

rings
Jupiter - Synchrotron
De Pater, Schulz & Brecht 1997
 = 20cm
3-D Reconstruction
Developed by
Bob Sault (ATNF)
- see Sault et al.
1997; Leblanc et
al. 1997; de Pater
& Sault 1998
Saturn

2nd biggest planet

Gas ball

“weather”

Rings
Saturn - Thermal Emission
van der Tak, de Pater, Silva & Millan 1997
 = 2cm
Titan

Bigger than Pluto

thick atmosphere
(haze/smog)

ice + liquid surface
Titan - Radar
Muhleman, Grossman, & Butler 1995
no global ethane/
methane ocean
maybe ‘seas’?