• Alison L. Mead

Halo

The halo over the sun this past weekend was meteorological, more associated with our atmosphere than astronomical. The halo was caused by high altitude ice crystals which reside from three to six miles in the air. When there is an over abundance of ice crystals in the atmosphere, a halo forms over the sun.

These ice crystals can also create a sun dog, an event very similar to a halo.

Extreme Tides

Tides this weekend are both extremely high and low. Tides are running high at close to noon and at close to midnight. Tides are running low around sunrise and sunset. Tides are created by the gravitational pull of the sun and moon, which will be higher than usual this weekend.

The moon is both full this weekend and particularly close. Full moon is Saturday. The moon is in perigee on Sunday, closer to the Earth than at any other time in its 28 day elliptical orbit around the earth. The moon is slightly more than 222,000 miles away; about 30,000 miles closer to us than when it is farthest from the Earth, in apogee.

The sun’s gravitational pull on the other side of the sky is also greater at the moment as the moon and sun are opposite in our sky.

This astronomical event happens about three or four times a year. The wrack line on all beaches will rise higher than usual. Sand bars that are usually underwater will be revealed.

Sunrise and Sunset
DaySunriseSunset
Fri., May 245:148:02
Sat., May 255:138:03
Sun., May 265:138:04
Mon., May 275:128:05
Tues., May 285:118:06
Wed., May 295:118:06
Thurs., May 305:108:07
Fri., May 315:108:08

Temperatures and Precipitations
DayMax (Fº)Min (Fº)Inches
May 1773520.00
May 1865420.00
May 1969460.00
May 2069550.19
May 2174560.01
May 227153T
May 237158T

Water temperature in Edgartown harbor: 63º F.

 

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