The month of February is named after the Latin Februum, which are rites of purification. Braving the long, cold nights of February to enjoy just a glimpse of the beauty and wonder of the sky can be very purifying and humbling.
Jupiter is slowly getting a little dimmer and smaller since it’s already a month past its opposition. The king of the planets still rules the night sky, rising several hours before sunset. At minus 2.5 magnitude, it is still about eight times brighter than Mars. Notice that Jupiter is slowly moving westward, or in retrograde motion through Gemini toward the constellation of Taurus. That will end March 6, when it will again take up its normal, prograde or eastward motion with respect to the fixed background of stars for the next eight months before it starts its next four-month-long retrograde loop.
Look for its four unique Galilean moons through a pair of binoculars, or look for good detail in its cloud bands through a telescope while Jupiter is still brighter and closer than usual. The nearly full moon will pass close to Jupiter on the 10th and 11th.
The biggest asteroid, Ceres, and the brightest one, Vesta, will be less than 4 degrees apart, making looping paths through Virgo just to the left of Mars. They will be less than one degree apart on July 1. An unseen third body is orbiting between them. NASA’s Dawn spacecraft will encounter Ceres exactly one year from now.
Mars will join Jupiter in the evening sky as it begins the month rising by 11 p.m. in the constellation of Virgo and ends the month rising around 9:30 p.m. The red planet nearly doubles in brightness during the month, and it will be close enough to detect some of its surface features in a telescope by the end of the month. But its northern hemisphere will experience its summer solstice on the 15th, which means its north polar ice cap may be too small to detect. Mars will nearly double in size by the time it reaches its opposition April 8. Watch as the waning gibbous moon will pass near Mars one hour before sunrise in the morning sky on the 19th and 20th.
Saturn starts the month rising around 1:30 a.m. in the constellation of Libra and will end the month by rising before midnight in the same constellation. This beautiful ringed planet glows with a soft golden light that is 15 times fainter than Jupiter. Through a telescope, you will see that its marvelous ring system is now tilted open nearly 23 degrees, which is close to its maximum and offers a dramatic view of its thousands of incredible rings. These rings are paper-thin at only about 25 feet thick. That is fully 16 million times smaller than the diameter of Saturn, which is about 10 times that of our earth.
Saturn reaches western quadrature, which means it will be exactly 90 degrees west of the sun, on Feb. 11. This is when the shadow of its globe on its rings will be the most prominent for the year. You may also be able to see up to four or five of Saturn’s 63 moons through a good amateur telescope. Saturn is approaching its own opposition May 10, which is just one month after Mars will reach opposition this year. The many resonances established within its ephemeral and quaking ring system and its moons are perfect examples of pure mathematics and physics at work.
Venus has returned to the morning sky after a long evening apparition just ended in January. Look for brilliant Venus about a half-hour before sunrise low in the eastern sky in Sagittarius. Our sister planet will still be at its maximum brilliancy for the year, at about 10 times brighter than Jupiter and fully 150 times brighter than Saturn. Venus will then be getting smaller and fainter again, but it will go from a very thin waxing crescent to 36 percent lit by the end of the month. Look for a thin waning crescent moon near Venus on the morning of the 26th. The next morning, the slightly thinner crescent moon will be just above Mercury, which will be hard to spot so low in the twilight, even with binoculars. Our first planet will make a good evening apparition during the first few days of the month. Look for Mercury low in the West-Southwestern sky 45 minutes after sunset just below the slender waxing crescent moon during the first two evenings of the month.
This is one of only two months each year when you have the best chance to see the extremely elusive zodiacal light. The other is before dawn in November. Now it is 80 minutes after sunset in the western sky. It can be seen as a tilted pyramid of eerie, faintly glowing light rising out of the western sky. Beyond being a challenge to find and a wonderful sight to behold, its subtle light can give us clues about the evolution of our solar system as we are looking billions of years back into history by carefully studying these tiny particles.
Ranging in size from 10 to 300 micrometers, which is a millionth of a meter, these particles are finely ground comet and asteroid dust. They form a complete pancake-shaped torus around the entire ecliptic plane of our solar system. You can only see a tiny portion of this torus twice a year when the angle of the ecliptic is the highest in relation to our horizon.
They have an overall reflectively of only 12 percent, which is the same as our moon. By comparison, our earth has a reflectivity coefficient, or albedo, of about 35 percent. This huge number of individual particles slowly spiral inward toward the sun, so they have to be constantly replaced by new dust from comets and asteroids. If they get down to 10 micrometers in size, they will be removed by solar radiation pressure. The particles are actually very far apart, about half a mile between the average-sized particle of about 100 micrometers. If they were just 10 times bigger, at 1 millimeter across, it would only take only one particle every five miles to produce the reflectivity that they exhibit.
Feb. 1. Look for Mercury just below the waxing crescent moon 45 minutes after sunset, low in the West-Southwestern sky.
Feb. 4. Clyde Tombaugh was born on this day in 1906. He would discover Pluto on the 18th of this month in 1930, when he was just 24.
Feb. 5. On this day in 1971, Apollo 14 landed on the moon. It was just the third manned mission to land on the moon and the last one that didn’t use a lunar rover to drive around on the surface of our only natural satellite. The two astronauts that walked on the moon this time were Alan Shepard and Edgar Mitchell. They gathered and brought 93 pounds of moon rocks back to earth.
Feb. 6. First-quarter moon is at 2:22 p.m.
Feb. 7. The first untethered spacewalk was done on this day in 1984. The Stardust comet probe was launched on this day in 1999.
Feb. 8. Jules Verne was born on this day in 1828.
Feb. 10. Look for the moon just to the right of Jupiter this evening, one hour after sunset in Gemini.
Feb. 11. The first Japanese satellite was launched on this day in 1970.
Feb. 14. On this day in 1990, Voyager 1 made a solar system portrait from space. The full moon is at 6:53 p.m. This is also known as the Snow or Hunger Moon.
Feb. 15. Galileo Galilei was born on this day in 1564. He would point a telescope skyward and make many amazing discoveries, including rings of Saturn, moons of Jupiter, phases of Venus and sunspots.
Feb. 19. Nicholas Copernicus was born on this day in 1473. He first suggested that the sun is actually the center of our solar system and not the earth. This was later proven by Galileo.
Feb. 20. On this day in 1962, John Glenn became the first American to orbit the earth.
Feb. 22. Last-quarter moon is at 12:15 p.m.
Feb. 23. Supernova 1987a is seen exploding on this day in the Large Magellanic Cloud in 1987. Pioneer 11 left the solar system on this day in 1990.