Sunday: Late tonight and early morning’s weather forecast: showers. Meteor showers, that is. The Quadrantid meteor shower peaks late tonight and early tomorrow morning between midnight and dawn. Meteor showers are named after the constellation from which the meteors appear to originate. That makes this shower mysterious because there isn’t any constellation with this name now. The shower was named after Quadrans Muralis, an obsolete constellation found in some early 19th century star atlases. These meteors appear to come from a point in the modern constellation Draco the dragon. This point is about three fists held upright and at arm’s length above the northeastern horizon at 1:00 a.m. This year, the Moon will be below the horizon so you may be able to see up to 100 meteors per hour. Meteors are tiny rocks that hit the Earth and burn up in the atmosphere. Most meteors are associated with the path of a comet. This shower consists of the debris from an asteroid discovered in 2003. Keeping with the comet-origin paradigm, astronomers think the asteroid is actually an “extinct” comet, a comet that lost all of its ice as it passed by the Sun during its many orbits. For more information about the Quadrantid meteor shower, go to http://earthsky.org/?p=155137.
Monday: If the Sun looks big today and tomorrow, your eyes are not playing tricks on you. The Earth is at perihelion at 10:52 p.m., Pacific Standard Time tonight. If you dig out your Greek language textbook, you’ll see that peri- means “in close proximity” and helios means “Sun”. So, perihelion is when an object is closest to the Sun in its orbit, about 1.5 million miles closer than its average distance of 93 million miles. Since it is winter in the Northern Hemisphere now, the seasonal temperature changes must not be caused by the Earth getting farther from and closer to the Sun. Otherwise, we’d have summer when the Earth is closest to the Sun. The seasons are caused by the angle of the sunlight hitting the Earth. In the winter, sunlight hits the Earth at a very low angle, an angle far from perpendicular or straight up and down. This means that a given “bundle” of sunlight is spread out over a large area and does not warm the surface as much as the same bundle in the summer. For the Northern Hemisphere, that very low angle occurs in December, January and February.
Say “goodbye” to Venus. It is moving close to the Sun in the sky and will soon be obscured by its light. It is just above the west-southwestern horizon at 5:00 p.m.
Tuesday: Saturn is about a half a fist to the right of the waxing crescent moon, low in the southwestern sky after sunset.
Wednesday: Jupiter is about a half a fist above the moon and two and a half fists above the south-southwestern horizon at 5:00 p.m.
Thursday: Has it been tough to wake up this past week? It should have been because the sunrise has been getting a little later since summer started. I know. I know. December 21 was the shortest day of the year. But, because the Earth’s orbit around the Sun is elliptical and not circular, the Earth does not travel at a constant speed. It moves faster when it is closer to the Sun and slower when it is farther away. This leads to the latest sunrise occurring in early January and the earliest sunset occurring in early December. Neither of these happen on the first day of winter. On the first day of winter, however, the interval between sunrise and sunset is the shortest, making it the shortest day of the year. For more information, go to http://goo.gl/SJC5r.
Friday: Mars is a little more than a half a fist above due southeast at 6:45 a.m. Its rival Antares is nearly one fist to the right of Mars.
The positional information in this column about stars and planets is typically accurate for the entire week. For up to date information about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
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