Wednesday, February 29, 2012

Mars Opposition 2012

Mars Opposition (火星大冲 in Chinese) for 2012 occurs on Sunday 4th of March at 4:04 am Singapore time.

Mars opposition means Earth is in the middle between the Sun and Mars as shown in the following diagram. This implies Mars is on the opposite side of the Sun as viewed from Earth. Thus, on this day, when the Sun sets in the west, Mars will rise from the east. And Mars should be visible in the sky for almost the whole night till next sunrise.

Image Credit: NASA Science --
The significance of opposition for scientist is that because of its closer distance and bigger apparent size in the sky, more detailed observations can be made. When this timing is taken into consideration in advance when planing spaceflights to the planet, more fuel and time can be save.

For amateur astronomers and stargazers, due to its close proximity and bigger apparent size, it presents the best opportunity to observe the planet visually and take photographs or video of it. The moons of Mars will also look brighter and easier to spot through a telescope due to this reason.

For this coming Mars opposition, you do not need to only wait for the precise 4.04 am timing to observe it. You can start to observe Mars few days before and after 4th of March as the changes in the apparent size and brightness of Mars is not very drastic.

During this period, the size of Mars as viewed from Earth will be 13.9 arc seconds at a brightness of -1.3 (the smaller this number, the brighter it represents). The Moon is 1800 arc seconds. So now you now the Mars does not grow bigger than the Moon during opposition, or any planet for that matter.

During the 2003 Mars opposition, its maximum size was 25 seconds and maximum brightness at -2.8 magnitude! Almost double of this year's upcoming opposition. The following is an illustration of its relative sizes during oppositions over the years taken by the Hubble Space Telescope. The 1997's diagram represents about 14.2 arc seconds which is quite close to 2012's 13.9 arc seconds. So you can use that as a visual comparison.

Image Credit: Hubble Site --

Mars opposition happens approximately every 2 years. So if you miss this, you will have to wait till 2014.

To find Mars in the sky, look towards East and the brightest red star-like object you can see will be Mars. At about 9:00 pm during this weekend, it should be around 23 degrees above the horizon as shown in the following diagram.

Mars is currently in the constellation Leo the Lion. To further confirm what you are seeing is Mars, look for a bunch of relatively bright stars to the left of Mars which form the constellation Leo. There are not much bright stars to its right when Mars is rising in the East.

To see some features of Mars, a binocular may not be sufficiently powerful. You need to see it through a telescope.

Weather permitting, my friends and I will be conducting a Mars observation session this weekend with our telescopes for the public to enjoy free of charge. Here are the details:

Date: 2 Mar 2012 (Fri) and 3 Mar 2012 (Sat)
Time: 7:00 pm -- 10:30 pm
Venue: Open space outside Toa Payoh Public Library (Toa Payoh Central)
Google Map :
Google Street View:
Admission: Free and open to public. You may bring along your telescope if you wish to.

Important Notice: Event is totally dependent on weather. May be cancelled last minute due to bad weather. Please check the following websites and twitter for the latest updates on the actual day:

In addition to observing Mars, we will be observing other celestial highlights of the night like Moon, Jupiter, Venus, Seven Sister and Hyades star clusters and Orion Nebula and many more depending on the quality of the clear sky.

So do come and join us with your family and friends and enjoy a fun-filled evening under the stars!

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