2017 Week 10: (March 5-11)

The next week there is not too much happening in the sky.  The Moon will reach its first quarter at 4:30 in the morning on Sunday.  The only really neat observation will occur on Saturday the 10th.  The brightest star in Leo will be visible extremely close to the Moon.  You will be able to see them in the same moderate angle telescopic field of view at 48'.   The chart below highlights this next week.

Date	Event
Mar 5	First Quarter
Mar 6	Mercury at Superior Conjunction
Mar 10	Regulus 0.8°N of Moon

Mercury will be at what is known as superior conjunction.  This happens when an inferior planet (planet inside Earth's orbit (Mercury or Venus)) lies on the opposite side of the Sun.  It is the point where the inferior planet is lined up behind(typically above or below) the Sun as viewed from the Earth.  When a planet is at inferior conjunction it lines up in front of the Sun.  The orbital plane of the planet usually takes it above or below the Sun as it is in conjunction.  However, on May 9, 2016, Mercury was at inferior conjunction right in front of the Sun.  I used a solar filter on my 8" telescope and actually saw Mercury pass across the face of the Sun.  This is a very rare event.  It happens around a dozen times a century for Mercury and around twice a century for Venus.  Fortunately the next transit of Mercury is coming up on November 11 starting at sunrise and continuing for three and a quarter hours.  If you are waiting for the next transit of Venus partly visible from Calgary, it will occur late in the fall on December 8, 2125.  The next transit of Venus fully visible from Calgary will be late in the 25th century on June 12, 2490.  Don't miss it.  Mark it on your calendar.

An image from the May 9, 2016 Mercury transit is shown below.

Transit of Mercury, Image credit: NASA's Goddard Space Flight Center/SDO/Genna Duberstein

The weather forecast for the week is not too optimistic.  The 2016-2017 winter trend of below average temperatures continues with little respite in sight.  Hopefully the clouds will stay away and you will be able to see the winter constellations before they set for the year.