The month of March is named for the planet Mars, which stood for the Roman god of war. March used to be the first month of the year back in the early Roman calendar, over 2,500 years ago. 

 March always marks the return of spring for us in the northern hemisphere. This year, that will happen at exactly 6:29 a.m. on Monday morning the 20th of March. That is also called the vernal equinox and can be further defined by the sun on the ecliptic crossing over the celestial equator on an upward path. When the sun crosses back over the celestial equator on a downward path, half a year later, that is called the autumnal equinox. Those are the only two days each year that the sun actually rises due east and sets due west. As we head towards winter, the sun rises more and more south of east and sets more and more south of west, and as we are heading into summer now as soon as spring starts, the sun will be rising farther and farther north of east and setting farther and farther north of west, creating the longer days and its higher path through our sky. All of this is simply the effect of the tilt of the Earth, which is currently 23.5 degrees and that defines the tropic of Cancer and the tropic of Capricorn. 

Within a few days of both equinoxes are also the only days that are exactly 12-hours long everywhere on Earth except for the poles. That can be seen as a very unifying factor from a scientific and celestial viewpoint. The sun rising and setting due east and due west on those two days also happens everywhere on Earth except for the poles. The reason that the equal nights and days don’t fall exactly on the equinoxes is that the Earth orbits in a slight ellipse around the  sun and not a perfect circle as was believed for about 1,000 years before Kepler came along and proved that it wasn’t true.

Now that it is warming up and the days are getting longer, it is a good time to head outside under the night sky and enjoy and assimilate just a tiny bit of the great beauty that always surrounds us. There are several good highlights to look for, but every clear night is a great night to get outside regardless of the season. Venus will put on a great show towards the end of the month as it will appear in both the evening and morning sky and its huge thin crescent may even be visible without binoculars. Then Mercury makes its best appearance for the year in the evening sky and Jupiter gets closer and higher and brighter approaching its opposition in early April. The best occultation of the year will occur on the fourth, but unfortunately the Northeast will be the only part of our whole country that will not be able to see any part of this great occultation of the moon and Aldebaran in Taurus. There will be a line cutting through Hartford, Connecticut, and the northern United States, along which this will be a very rare graze occultation, meaning that the star Aldebaran will blink on and off several times as its light gets covered and uncovered by the mountains and the valleys on the moon right along the edge of its northern limb. This is the same cause for Bailey’s beads, which happens right before and right after totality during a total solar eclipse, like the one the entire country will enjoy this summer on Aug. 21. 

Brilliant Venus was at its very best and brightest in five years during the middle of last month. Now you can watch its dramatic decline from 32 degrees high in the western sky at sunset to 0 degrees just over three weeks later as our sister planet disappears below our western horizon. It will reach inferior conjunction on Saturday the 25th. That is the closest it gets to Earth for each cycle of 1.6 years. Its crescent will be very thin and huge and you may even be able to see it without binoculars or a telescope that evening and a few evenings before that. Its huge crescent will cover almost one minute of arc of the sky, or just 30 times less than the full moon covers at half a degree or 30 minutes of arc. 

Look for something even more unusual this time around. Since Venus will pass more than 8 degrees north of the sun during this inferior conjunction, which is much farther north of the sun than it usually gets at this time, you will actually be able to see this planet both in the evening sky after sunset and in the morning sky before sunrise. This will happen for more than a week around the 25th.  Start looking for Venus before sunrise as early as March 15. By March 22, Venus sets 30 minutes after the sun, but already rises 33 minutes before the sun the next morning. That time will extend to 40 minutes by the 25th.  Try to look at Venus with a telescope during this time and look for wispy cusp extensions of its thin crescent. These are caused by the back scattering of sunlight through the thick atmosphere of Venus. The only time this is more dramatic would be right before or after a transit of Venus, which happens eight years apart and then not again for another 121.5 years as the Earth, sun and Venus plane doesn’t align very often. I saw both of the last two transits in June of 2004 and June of 2012. 

Venus is a very strange planet. Its surface temperature is almost 900 degrees Fahrenheit, hot enough to melt some metals like lead and tin. At its surface, its air pressure is almost 100 times more than ours on Earth. At about 40 miles above the surface of Venus, its pressure equals ours on the surface of Earth. The enormous pressure on Venus is similar to being 3,000 feet under the ocean on Earth. Its atmosphere has high levels of carbon dioxide since infrared light from the sun can get through its atmosphere, but then some of those rays can no longer escape back out into space. That is what makes a greenhouse on Earth work, but there is way too much carbon dioxide in the atmosphere of Venus. Its atmosphere is over 96 percent carbon dioxide and only about 3 percent nitrogen. Ours is about 78 percent nitrogen and 21% percent oxygen and a few other trace elements. We only have about 400 parts per million of carbon dioxide.

One year on Venus equals 225 days, but one single day is equal to 243 Earth days. Venus also spins in the opposite direction of most planets, so the sun actually rises in the west each morning, but that is not very often. Even more interesting than that, Venus makes 13 trips around the sun every eight years and reaches an inferior conjunction with Earth five times in those eight years, or every 1.6 years. That is the famous golden ratio, also known as phi. The other three numbers are all Fibonacci numbers. That is the famous sequence that you get by simply adding the two previous numbers to get the next number. The ratio of any two of these numbers is 1.618. Many things in nature grow this way including sunflowers and galaxies and twigs on a branch. 

Look for orange Mars about 15 degrees up and to the left of Venus. Mars continues to fade slowly, but it is still brighter than any nearby stars. The red planet sets a little earlier each night, but we will not lose it completely until early July. After that, it will just show up again in the morning sky. It is about as far away from Earth now as it can get. Saturn continues to rise a little earlier each night in Scorpius. The ringed planet now rises soon after 1 a.m. It will not reach opposition until the middle of June, just before summer starts. 

March 1. Mars and Venus are near the moon this evening.

March 4. The moon in the Hyades in Taurus occults Aldebaran tonight. 

March 5. First quarter moon is at 6:33 a.m. EST. 

March 12. Full moon is at 10:55 a.m. EST. This is also called the Worm, Crow, Sap, or Lenten Moon. Daylight-saving time starts at 2 a.m. this Sunday.

March 13. On this day in 1781 William Herschel discovered the planet Uranus.

March 14. Albert Einstein was born on this day in the year 1879. Jupiter, Spica, and the waning gibbous moon form a nice triangle in the east around 10 p.m.

March 20. Last quarter moon is at 11:59 a.m. EDT. Saturn will be near the moon this morning. 

Spring starts at 6:29 a.m. EDT this Monday morning. 

March 22. On this day in 1997, Comet Hale-Bopp made it closest approach to Earth.

March 25. Venus reaches inferior conjunction with the sun tonight.

March 27. New moon is at 10:58 p.m. 

March 29. Mars is near the slender waxing crescent moon this evening and the next.