Follow Comet Siding Spring on Google+

Comet Siding Spring is due to make a close flyby of Mars tonight at 20:28 South African time and to celebrate the close encounter, the South African Astronomical Observatory (SAAO), together with Living Maths, will be hosting a Google+ hangout from 20:00 to 21:00 with a live audience at the SAAO.

Comet Siding Spring is due to make a close flyby of Mars on tonight at 20:28 South African time. It will pass at a distance of just 140,000 km, or about one third of the distance between the Earth and our Moon. This is ten times closer than any known comet has flown by Earth and the comet will be hurtling along at a speed of about 56 km/s.

To celebrate the close encounter, the South African Astronomical Observatory (SAAO), together with Living Maths, will be hosting a Google+ hangout from 20:00 to 21:00 with a live audience at the SAAO to discuss the close flyby and all things comet and space related. The Google+ hangout will be streamed live over the internet at the Living Maths website (http://www.livingmaths.com/).

During the hangout, astronomers from the SAAO in Cape Town and Sutherland will be joined by NASA’s deputy chief technologist Jim Adams, Dr Padma Yanamandra-Fisher, a senior research scientist at the Space Science Institute in Rancho Cucamonga, California, Dr Henry Throop, a planetary scientist based at the University of Pretoria, and representatives from the Cape Town chapter of the Astronomical Society of Southern Africa.

Living Maths director Steve Sherman will be running the hangout. Questions can be emailed to him on livmath@iafrica.com or by tweeting @livingmaths. There is no cost to attend the event at SAAO, but as space is limited online booking is essential, at http://www.livingmaths.com/event/nasa-interview-19-october/ or call the SAAO on 021 447 0025.

The comet, officially known as Comet C/2013 A1, was discovered in January 2013 by astronomer Rob McNaught, using Australia’s Siding Spring Observatory. Comet Siding Springs originates from the Oort Cloud which surrounds our solar system, lying between 5 000 and 100 000 times further from the Sun than Earth does. The comet is currently making its first trip into the inner solar system. Because it has not been exposed to the Sun before, it is thought to be unchanged since its formation around 4.5 billion years ago. By studying the comet, scientist hope to learn more about the materials and conditions that existed at the birth of the solar system.

In addition to its two rovers on the surface, NASA has three operational spacecraft in orbit around Mars. The European Space Agency and India also have spacecraft in orbit. All the probes are expected to be part of a mammoth observing campaign to study the comet during its Martian encounter.

The goal is to learn more about the comet itself, its size, rotation speed, activity and composition. Additionally, interactions between the comet’s particles and Mars’ atmosphere may also help scientists better understand Mars’ atmosphere.

NASA’s plans to take the first-ever good pictures of an Oort Cloud comet’s nucleus using its Mars Reconnaissance Orbiter (MRO) spacecraft. Rovers Opportunity and Curiosity could also make history by taking the first images of a comet from another planet.

To ensure that none of their satellites orbiting Mars are damaged during the close encounter, NASA has opted to tweak its satellites’ orbits. They will be behind the planet as the comet’s dust tail passes, which starts about 100 minutes after closest approach. The thin Martian atmosphere will shield NASA’s Opportunity and Curiosity rovers from cometary dust.

Some data from observations of the comet have already been analysed. Scientist think that the comet’s core (nucleus) is between 0.8 and 8 km in diameter. The coma, the fuzzy cloud surrounding the cometary nucleus, is about 19 300 km wide currently, and its dusty tail stretches for about 480 000 km. However, astronomers will learn much more about the comet during the close encounter itself.

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