Tonight (2/22/12), just after sunset, we have an opportunity to see a very interesting conjunction. The one day old crescent Moon will be very near the planet Mercury just above the western horizon. Mercury is the closest planet to the Sun and never gets very high in the sky. This week and next will be the best viewing window for Mercury for 2012. Brighter Venus and Jupiter will provide a line you can trace towards the horizon to find Mercury. The Moon will be such a thin crescent you may have to use Mercury to find it!
On Saturday (2/25/12) evening the slightly thicker crescent Moon will be spectacularly close to Venus. On the following evening (2/26/12) it will be near Jupiter but not quite as close as it was to Venus.
Orion also gives you a great opportunity to see if you can discern color differences in stars. The upper left star (Orion’s right shoulder as he’s facing you) is the star Betelgeuse, a red supergiant. The lower right star (Orion’s left foot) is the star Rigel – a blue supergiant. Rigel and Betelgeuse are the 6th and 8th brightest stars in the night sky respectively. See if you can see the color difference the next time you view Orion. You will then start to notice color differences in other stars throughout the sky!
This time of year is a great time to view one of the most recognizable constellations in the night sky – Orion. He’s standing upright above the southern horizon around 7:00 PM CST these days. The three stars that form Orion’s belt are instantly recognizable. Playing the part of the sword hanging down from the belt are several bright stars embedded in a fuzzy patch – the Orion Nebula.
Take some some this Valentine’s Day to view Venus above the southwest horizon at twilight and shifting towards the west as it gets later. The planet is named after the Roman goddess of love and beauty. You can then contemplate the irony of the name. While similar in size to the Earth, we know that the conditions at the surface are much more extreme. Atmospheric pressure is roughly 100 times that of Earth and temperatures can exceed 900 degrees F.
There’s lots of great stuff going on in the evening sky right now. Why not start with the bright planets? From twilight to several hours now after dark, look for Jupiter high above the southern horizon and Venus above the southwestern horizon. They are easy to spot because they are so bright and have been moving closer together. We can look foward to a conjunction on March 13th. Slightly dimmer Mars rises above the eastern horizon around 7:00 PM CST. The waning gibbous Moon will be nearby over the next couple days. Mars is also visible if you are an early riser. Look high above the south-southwest horizon in the hours prior to sunrise. It has a distinctly reddish appearance and is getting brighter as it nears opposition in March.
If you looked high above the southern horizon around twilight the last two evenings (January 29 and 30) you had a good shot at seeing Jupiter very near the waxing crescent Moon. Faithful readers may remember I pointed out a Jupiter-waxing gibbous Moon conjunction back on January 2nd. Here is a picture I took of that conjunction:
The view the last two nights was subtly different. Jupiter has shifted further west in the sky at about the same time of night. So the waxing crescent Moon drew near Jupiter as opposed to the waxing gibbous Moon. The night sky is dynamic if you view it for more than just a few minutes. Changes occur due to the relative motions of the Earth and other planets. Jupiter is currently moving further away and is not nearly as bright as it was back in October/November when it was nearer to us.
Look above the southwest horizon tonight (January 25th) and tomorrow night around twilight to see Venus and the waxing crescent Moon very near to one another once again. We saw this pairing back on December 26th and 27th and it will come around again in approximately one month.
At a month out from the December southern solstice have you noticed the daylight period getting longer? I was out at 5:00 PM (CST) last night and it was still bright. At 6:00 PM a few nights ago I noticed there was still light in the west. The path of the Sun on the celestial sphere continues to creep northward and we see subtle signs of the changes that lay ahead.
January 19, 2012 marks the six year anniversary of the launch of the space probe New Horizons currently on its way to the first close encounter with the dwarf planet Pluto. New Horizons left Earth traveling at greater than 36,000 miles per hour and will still take another three years to reach Pluto, arriving around July 14, 2015. At approximately two-thirds of the journey completed there are still about a billion miles to go, a testament to Pluto’s extreme distance from the Earth.
Why go to Pluto? Humanity has not yet had a close encounter with an object beyond the orbit of Neptune. These objects are small and dim – very dfficult to study at their extreme distance. The maps shown below courtesy of NASA and the ESA and obtained via the Hubble Space Telescope are among the highest resolution images we have of the surface of Pluto.
Many people are aware that planetary orbits in our Solar System are not perfectly circular and the Sun is not at the exact center of the orbit. Therefore planets have a point in their orbit where they are closest to the Sun (called perihelion) and a point where they are furthest from the Sun (called aphelion). Today Earth reaches perihelion. Many people are surprised to learn perihelion occurs in the dead of winter for the northern hemisphere. However, we must not be northern hemisphere centric: recall it is summer in the southern hemisphere, indicating the distance from the Sun has very little to do with the seasons. In fact, Earth’s orbit is nearly circular and the difference in distance at perihelion and aphelion is relatively small.
We’ll talk more about the seasons in March when we reach the March equinox.
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This is a weekly blog updated by Jeff Butikofer.