When you want to see the stars, find someplace dark
Sky events
Occurring with this full Moon is a partial lunar eclipse. This eclipse is fairly modest, only about 25% of the Moon will be immersed in the earth’s inner shadow. For the islands the event will be even more unremarkable as the penumbral stage will have just begun prior to moonset and none of the partial eclipse will be visible. The timing of this eclipse favors Australia and Asia.
For the islands the next good lunar eclipse will occur Jan 31, 2018.
As I gazed up at a nearly full Moon this evening I realized that the countdown is quite short now. When that Moon is new again it will pass in front of the Sun to create a total solar eclipse.
I have been anticipating and planning this trip for many years. It was after the transit of Venus in 2012 that I really turned my attention to the next major astro-event. Laying out plans to camp somewhere in Eastern Oregon where the viewing is likely to be excellent.
On August 21 this year a total solar eclipse will sweep cross the mainland United States, something that has not happened since 1979.
Our plan for this eclipse? A little preliminary yet, but starting to shape up. Eastern Oregon should provide a good chance for a clear view in August. Stay in the LaGrande area with family, heading south on eclipse day to a good vantage point near the center-line. Most likely somewhere south of Baker, Oregon. There are a lot of high elevation meadows and mountain roads that should provide a memorable place from which to view this eclipse.
Today Mercury will be at maximum eastern elongation, as high in the evening sky as it will appear for this current apparition. After today the planet will slide back into the sunset, passing through inferior conjunction on August 26th to reappear in the morning sky in mid-September.
There are no transits of Mercury in 2017, the next will be Nov 11, 2019.
Tomorrow morning, July 20th, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 11% crescent a little over 4° from Venus shining at -4.0 magnitude. The pair will rise about three hours before sunrise a bit before 2am, look for the two above the brightening glow of dawn.
Today the Earth is furthest from the Sun, a point called apehelion. We will be about 152,096,000km (94,508,000miles) from the Sun. Compare this to the 147,099,000km (91,403,000miles) we were at perihelion on January 4th, a difference of about 4,996,000km (3,104,000miles) occurring throughout one orbit.
It may seem odd that we are actually at the furthest for the middle of northern summer, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.
| 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 | ||||
Today Mercury will be at superior conjunction. After today the planet will reappear in the evening sky, rising high enough from the Sun’s glow to be seen early next month.
As Mercury is on an orbit inside that of Earth’s it will see both inferior and superior conjunctions as it passes from the evening sky to the dawn sky and back again.