Skywatch Line for Wednesday, January 3rd, and Thursday, January 4th, 2018

This is the Dudley Observatory Skywatch Line for Wednesday, January 3rd, and Thursday, January 4th, written by Louis Suarato.

Our planet reaches perihelion, its closest distance to the Sun for year, on Wednesday at 1 a.m. EST. At that time Earth will be 91,401,983 miles from the Sun. Earth orbits the Sun at an average distance of 92,955,807 miles throughout the year. Earth will be at its closest point to the Sun, known as aphelion, on July 6th, at a distance of 94,507,803 miles. As we in the northern latitudes know, perihelion has little to do with seasonal temperatures. Our planet orbits the Sun with its axis tilted at 23.5 degrees. During the winter months, and at the time of perihelion, Earth’s axis is tilted away from Sun, causing the Sun’s rays to strike the northern hemisphere’s surface less directly. The opposite is true for the southern hemisphere.

The axial tilt also affects the amount of daylight we receive. The further the Earth is tilted away from the Sun, the shorter the day. The Earth is tilted furthest away on the Winter Solstice, the shortest day of the year. Although we’re past the time of the Winter Solstice and the shortest day, January 4th will give us the latest sunrise of the year. Once again, it is the axial tilt that contributes to the uneven changes in the times of sunrise and sunset.

The 95% illuminated, waning gibbous Moon rises at 6:42 p.m. Wednesday. Look for the Beehive Cluster, also known as M44, 5 degrees above the Moon. Thursday is the birthday of amateur astronomer Wilhelm Beer. Born in 1797, Beer produce the large-scale map of the Moon based on his observations with a Fraunhofer refractor. The lithographed map provided the most complete details of the lunar surface during the 19th century. Mars rises at 2:57 a.m., followed by Jupiter 6 minutes later. The two planets are a degree apart. Look for Mercury after 6 a.m., low in the southeast.

One of the best meteor showers of the year will be overwhelmed by a close, gibbous Moon, and bad timing for a narrow peak that occurs during daylight hours. The Quadrantid Meteor shower, which can yield as many as 120 shooting stars an hour, peaks at 3:13 p.m. Wednesday. The radiant for this shower is in the constellation Bootes. Bootes rises in the northeast after midnight, but if you want to brave the cold and attempt to view some meteors, you may want to look for them early Wednesday and Thursday before dawn.

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