Luna
Category: Astronomy
Exploring the cosmos
Tropical Snowplow
Earth at Perihelion
Today the Earth is closest to the Sun, a point called perihelion. We will be about 147,099,000km (91,403,000miles) from the Sun. Compare this to the 152,096,000km (94,508,000miles) we will be at aphelion on July 3rd, a difference of about 4,996,000km (3,104,000miles) occurs throughout one orbit.
It may seem odd that we are actually at the closest for the middle of northern winter, 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 | ||||
Control Logic
Quadrantid Meteor Shower Reminder
A reminder that tonight is the peak of the annual Quadrantid meteor shower. Peak will occur around 04:00HST tomorrow morning, January 3rd. Given our 20° latitude here in Hawaii the radiant does not rise until 01:30HST, thus observations must wait until well into the morning hours. A first quarter moon will set early leaving a perfectly dark morning sky for meteor observing.
Watching meteors requires no more equipment than your eyes and a dark sky, and can be enjoyable for just about anyone.
The Sky for 2017
Looking ahead to 2017 it appears that the skies will be kind to us this coming year. We have good meteor showers, a total eclipse of the Sun, a bright comet or two, and the usual planetary conjunctions to look forward to. Below you will find some on my notes to what we can look forward to during the coming year.
Covered are elongations for Mercury and Venus, interesting conjunctions, oppositions, eclipses and meteor showers. Posts include notes for visibility in the Hawaiian islands for those events that are location dependent.
The Moon and Venus
Look for the two as the evening sky begins to darken, they will not be difficult to find. Tomorrow the Moon will have moved 7° to the east of Venus.
Fireworks
The new year is upon us. Of course that means plenty of fireworks here in the village. It will be a noisy night!
Wiring
Snow on the Summits
A gorgeous image released by NASA’s Earth Observatory this week. it features the recent snowfall atop our island’s summits. I suggest you go to the link above, download the 6k x 6k version, then just zoom in and enjoy the detail! (Sorry the full image is bigger than the WordPress size limit to post here)
