All you ever wanted to know about eclipses and other celstial bodies
Comet Siding Spring (C/2013 A1)
(Oort Cloud Comet) - Comet Siding Spring (C/2013 A1) - Mars fly-by 19 October 2014
Comet Siding Spring (C/2013 A1) was discovered by, Robert H. McNaught at Siding Spring Observatory in Australia.
Closest Approach to Mars, 19 October 2014, 18:28 UT/GMT (11:28 AM PT/2:28 PM ET).
Siding Spring nucleus is small at less than a mile in diameter/1.6km, but it's speed is high and it flew passed Mars at about 34.79 miles per second (56km/s) [125,268 miles per hour/201,600 km/h]. It's closest appraoch to Mars was at a distance of about 87,000 miles/139,500 km. (equivalent to about one-third of the distance between Earth and the Moon).
At the time of its discovery, Comet Siding Spring was farther from the Sun than the planet Jupiter, or about 7.2 times farther away from the Earth to the Sun.
McNaught discovered the comet on 03 January 2013, using the 0.5-meter (20-inch) Uppsala Schmidt Telescope, at Siding Spring Observatory in New South Wales, Australia. It was a remarkable achievement because comet Siding Spring was approaching from underneath the plane of Earth's orbit.
Below; Hubble Image of Comet Siding Spring.
Comet Siding Spring (C/2013 A1)
Hiding the Mars Spacecraft - just to play it safe
NASA call it Duck and Cover
The chances of any comet dust impacting the various spacecraft orbiting Mars was minimal, nevertheless it made sense to be wise and play it safe, so a decision was made to "hide" the spacecraft in the shadow of Mars until the comet has passed. It allowed the planet to absorb any potentially damaging high-speed dust particles that trailed the comet.
Comet Siding Spring Trajectory; click on image to enlarge
image credit NASA
Comet Siding Spring - Hiding Mars Orbiters Spacecraft - click image to enlarge
The close fly-by of Mars by Comet Siding Spring is unique, unexpected, and lucky for us
Space scientist David Humm of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland said, "This comet is coming into the solar system straight from the Oort Cloud. It's likely this is its first time this close to the sun. The close fly-by of Mars by Comet Siding Spring is unique, unexpected, and lucky for us.”
artist's concept Comet Siding Spring (C/2013 A1) 19 October 2014. image credit NASA/JPL-Caltech
Hiding the Mars Orbiting Spacecraft - Time of Greatest Risk - was a wise decision
Although damage from the dust of Comet Siding Spring was small, the greatest risk to orbiting spacecraft was approximately 90 minutes after closest approach of the comet's nucleus, which lasted for about 20 minutes, and this was when Mars came nearest to the centre of the widening trail of dust spraying from the nucleus. Hiding the Mars Spacecraft - just to play it safe - made sense, and so the manoeuvring of the spacecraft behind the planet, which NASA calle it, 'Duck and Cover' was a wise decision.
video - Comet Siding Spring: A Close Encounter with Mars - NASA Jet Propulsion Laboratory
(Oort Cloud Comet) - Comet Siding Spring (C/2013 A1) - Mars fly-by 19 October 2012
Comet Siding Spring (C/2013 A1). Closest Approach to Mars is on 19 October 2014, 18:28 UT/GMT (USA: 11:28 AM PT/2:28 PM ET) (India: 23:58 IST; India Standard Time) (05:28 AEDT - Australian Eastern Daylight Time – Monday 20 October)
Earth-based telescopes and space telescopes tracking Comet Siding Spring (C/2013 A1)
Earth-based telescopes and space telescopes, including the Hubble Space Telescope will be in position to observe Comet Siding Springs. NASA’s astrophysics space observatories will also be looking which include; Kepler, Swift, Spitzer, Chandra. The ground-based Infrared Telescope Facility on Mauna Kea, Hawaii, will also be tracking the celestial object.