David L. Richards

Five planets can be seen at the same time this week.

Jupiter rises on Monday at about 9 p.m. in the constellation Leo, the Lion.

Mars follows, at 1:30 a.m. in Libra, close to the star Zubenelgenubi. Saturn rises at 3:48 a.m. in Ophiuchus, and by 6:20 a.m. on Tuesday morning, Venus and Mercury appear on the eastern horizon. These five planets can be seen simultaneously all week.

You could see all eight planets on Tuesday as Neptune and Uranus sit in the southwest at 7 p.m. (Look down for the eighth.) If you had an enormous telescope you could also see the five dwarf planets that day.

On Saturday morning, Mercury and Venus are within 4 degrees of the waning crescent moon. The waxing crescent moon and Uranus are within the field of a pair of 7 x 50 binoculars on the evening of Feb. 12. The giant planet Jupiter and the waning gibbous moon are separated by only 2 degrees on the night of Feb. 23.

Q&A

Q: On New Year’s Day, I got into an argument about just how long the year is. Exactly how long is a year? — J.N., Canton

A: At least four different measures can be made to describe one Earth year. The sidereal year — 365 days, 6 hours, nine minutes and 10 seconds — is the time it takes for Earth to complete one revolution of its orbit as seen against the stars.

The tropical year is the time between one spring equinox and the next, and is 365 days, 5 hours, 48 minutes and 45 seconds long. The tropical year is the unit of time used by navigators, astronomers and physicists.

The anomalistic year is the time it takes the Earth to complete one revolution with respect to where the Earth is closest and farthest from the sun, and that is 365 days, 6 hours, 13 minutes and 53 seconds.

There are also the draconic and lunar years, which are measured against lunar phenomena, and helical and Sothic years, measured against … you get the idea, so let’s skip these arcane terms.

What most of us think of is a calendar year begins on Jan. 1 and ends on Dec. 31, and is 365 days long; but clearly this is a compromise and a human construct to simplify the above, as we have to insert a leap day every four years. Take your pick.

Programs

The planetarium offers a new adult astronomy program at 2 p.m. on the first Monday of every month. The Night Sky show is presented, then participants engage in a 30- to 45-minute open lecture/discussion, driven by the audience’s interests and questions concerning astronomy and cosmology.

The regular planetarium show, The Universe at Large, is presented at 1 p.m. Saturdays and 2 p.m. Sundays. It is included with admission to the museum. Children must be 5 years or older to attend.

David L. Richards is director of the Hoover-Price Planetarium at the McKinley Presidential Library and Museum, 800 McKinley Monument Drive NW, Canton, www.mckinleymuseum.org. He can be reached at 330-455-7043, email hooverpriceplanetarium@hotmail.com or read his blog at https://hooverpriceplanetarium.wordpress.com/.