Chronicnerd wrote:As a side note about Phobos:
Radius of moon: 6.9 miles (11.1 km)
Hmmm... trying to do "quick math" here...
So, Phobos is about 10659000000000000kg according to the Wikipedia entry and is about 11.1km (average) in diameter. While this is *not* perfect calculations,
Statistics: Posted by Chronicnerd — Tue Oct 21, 2014 3:50 pm
the diameter is about 22.2 kms
Statistics: Posted by The57ironman — Tue Oct 21, 2014 3:34 pm
Statistics: Posted by DarkHeart — Tue Oct 21, 2014 10:04 am
Statistics: Posted by The57ironman — Tue Oct 21, 2014 4:12 am
The origin of the Martian moons is still controversial. Phobos and Deimos both have much in common with carbonaceous C-type asteroids, with spectra, albedo, and density very similar to those of C- or D-type asteroids. Based on their similarity, one hypothesis is that both moons may be captured main-belt asteroids. Both moons have very circular orbits which lie almost exactly in Mars's equatorial plane, and hence a capture origin requires a mechanism for circularizing the initially highly eccentric orbit, and adjusting its inclination into the equatorial plane, most probably by a combination of atmospheric drag and tidal forces, although it is not clear that sufficient time is available for this to occur for Deimos. Capture also requires dissipation of energy. The current Martian atmosphere is too thin to capture a Phobos-sized object by atmospheric braking. Geoffrey Landis has pointed out that the capture could have occurred if the original body was a binary asteroid that separated under tidal forces.
Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large planetesimal. The high porosity of the interior of Phobos (based on the density of 1.88 g/cm3, voids are estimated to comprise 25 to 35 percent of Phobos's volume) is inconsistent with an asteroidal origin. Observations of Phobos in the thermal infrared suggest a composition containing mainly phyllosilicates, which are well known from the surface of Mars. The spectra are distinct from those of all classes of chondrite meteorites, again pointing away from an asteroidal origin. Both sets of findings support an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's moon.
Statistics: Posted by Chronicnerd — Tue Oct 21, 2014 3:01 am
Statistics: Posted by nearlyaminion — Tue Oct 21, 2014 2:20 am
the flyby of Mars, October 19, 2014. While comet Siding Spring will reach perihelion just 6 days later, October 25, 2014, it will hardly have sensed the true power and impact that our Sun can have on a comet.
Comet Siding Spring was at its closest point to Mars at 18:27 UTC on October 19th, 2014, its perihelion (its closest point to the Sun) occurs on October 25th. The comet has already reached a peak magnitude of +9.6 on September 9th.
Statistics: Posted by Shaggietrip 2.5 — Tue Oct 21, 2014 1:15 am
The actual orbital distances of Phobos and Deimos are 1.4 and 3.5 Martian diameters, and their respective orbital periods are 7.6 and 30.3 hours.
Statistics: Posted by The57ironman — Tue Oct 21, 2014 12:53 am
Statistics: Posted by Funnyman46 — Tue Oct 21, 2014 12:44 am
Upload to Disclose.tv
CSIRO Australia Telescope Compact Array observations of a jet of energetic particles emitting radio waves (shown in pink), coming from the star IRAS 15445-5449. [color=#FF0000]Dusty material around the star (shown in green) was imaged with ESO's Very Large Telescope Interferometer. The star itself is hidden by dust. Credit: A. Pérez-Sánchez /ATCA/CSIRO; E. Lagadec/ESO
Read more at: http://phys.org/news/2013-09-magnetic-f ... r.html#jCp
Statistics: Posted by Shaggietrip 2.5 — Tue Oct 21, 2014 12:30 am