Archive for January, 2012
Look above the southwest horizon tonight (January 25) 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 26 and 27 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.
The Quadrantid meteor shower peaks in the early morning hours of January 4 (the previous evening being January 3) and should be an excellent display this year for the eastern United States. The Quadrantid meteor shower is often cited as the third best meteor shower - coming in behind the Perseids in August and the Geminids in December. I mentioned the Leonids back in November and the Geminids in December and both showers had a bright Moon interfering with them. In the eastern US, the waxing gibbous Moon should set around 3:00 AM leaving a window of viewing opportunity until dawn. The meteors will appear to originate from a point above the east-northeast horizon. Normally, one might not even consider going outside in the early morning hours in January but, in northeast Iowa the forecast is for a low of 23 degrees F. While this sounds cold, it is well above our average for this time of year.
The best International Space Station (ISS) viewing opportunity for northeast Iowa in the next couple weeks occurs tonight, January 3, at 5:47 PM. The ISS will arrive in view low above the west, northwest horizon and will depart from view low above the southeast horizon. Note that this trajectory takes it essentially across the sky and it will be visible for 6 minutes. Because it is very bright and moving quickly, it is difficult to miss if you are looking in the correct general vicinity at the right time. The direction and time information given is for the general area around Waterloo, IA. For viewing opportunities at your location or for additional viewing opportunities be sure to visit the following link and enter the pertinent information for your location:
Look high above the southeast horizon tonight (January 2) to see bright Jupiter and the waxing gibbous Moon very close to one another. We’ve been talking about Moon phases recently. January 1 saw the Moon at 1st quarter – a quarter of the way through its cycle of phases and it appeared 50% illuminated to us, with the right half illuminated in the northern hemisphere. Between 1st quarter and full Moon are the waxing gibbous phases with the illuminated portion of the Moon growing larger than 50% but not quite full.