Category: Sky Events

Sky events

Summer Solstice

Summer solstice occurs today at 18:24HST. Today the Sun will occupy the most northerly position in the sky of the year. The term solstice comes from the latin terms Sol (the Sun) and sistere (to stand still). On this day the Sun seems to stand still as it stops moving northwards each day and begins move to the south. This is the first day of summer as marked by many cultures in the northern hemisphere. Alternately this is the first day of winter for those living south of the equator.

This year many calendars will mark September 21st as the summer solstice, and so it is for much of the world. Here in Hawaiʻi the solstice actually occurs on the 20th when considering the time zone differences.

2017 Solstices and Equinoxes
  UT HST
Perihelion Jan 4 14:18UT Jan 4 04:18HST
Vernal Equinox Mar 20 10:29UT Mar 20 00:29HST
Summer Solstice Jun 21 04:24UT Jun 20 18:24HST
Apehelion Jul 3 20:11UT Jul 3 10:11HST
Autumnal Equinox Sep 22 20:02UT Sep 22 10:02HST
Winter Solstice Dec 21 16:28UT Dec 21 06:28HST
Source: USNO data Services

 

The Moon and Venus

Tomorrow morning, June 20th, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 18% crescent a little under 6° from Venus shining at -4.2 magnitude. The pair will rise about three hours before sunrise at about 2am, look for the two above the brightening glow of dawn.

e Moon, Venus and Aldebaran
The Moon, Venus and Aldebaran join up for an evening conjunction

Saturn at Opposition

Today the planet Saturn will pass through opposition, directly opposite the Sun in our sky.

Saturn 22Apr2010
Saturn with Titan above
Saturn orbits the Sun once every 29.45 years. As the ringed planet continues on its way the Earth swings around much faster on our inside track. As a result we lap Saturn once every 378.1 days, passing between the planet and the Sun. During opposition Saturn will be well placed for observation all night long, rising at sunset, transiting at midnight, and setting at sunrise.

During opposition the planet and rings will be slightly brighter than normal, an effect known as the opposition effect. The effect is most notable in the rings where the apparent brightness can increase by 30%. The effect is a combination of two factors, shadow hiding and the retro-reflective properties of the ring particles.

Venus at Maximum Elongation

Today Venus is at maximum elongation, as high in the dawn sky as it will get for this morning apparition, about 45.9°. After today the planet will begin its slide back into the glare of dawn. It will disappear from view around the end of the year and reach superior conjunction on January 8th, 2018.

As Earth and Venus race about the Sun, Venus will complete about one cycle of appearances each year. We can expect one evening apparition and one morning apparition to occur in 2017.

Continue reading “Venus at Maximum Elongation”

The Moon and Venus

Tomorrow morning, May 22nd, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 15% crescent a little over 3° from Venus shining at -4.4 magnitude. The pair will rise about two hours before sunrise at about 3am, look for the two above the brightening glow of dawn.

e Moon, Venus and Aldebaran
The Moon, Venus and Aldebaran join up for an evening conjunction

Mercury at Maximum Elongation

Today Mercury will be at maximum western elongation, as high in the morning sky as it will appear for this current apparition. After today the planet will slide back into the dawn, passing through superior conjunction on June 21st to reappear in the evening in mid-July.

Mercury Transit 9May2016
Mercury transiting the Sun on May 9, 2016. Celestron C8 and Canon 6D at f/10.
This will be the best morning apparition of the inner planet for 2016. The best evening apparition of 2017 will be in July, with a maximum elongation of over 27°.

There are no transits of Mercury in 2017, the next will be Nov 11, 2019.

Continue reading “Mercury at Maximum Elongation”