St. Thomas Skywatch July – October 2017
Over these months the sky over the Virgin Islands will dazzle with planets, stars, meteors, and an eclipse of the Sun.
As the sky grows dark, high in the west is the very bright star-like object Jupiter. Just south of Jupiter is the bright star of Spica, a grain of wheat being held in the hand of Virgo, the goddess of the harvest. At the same time, high in the southern sky is a bright red star, Antares, the red heart of Scorpius, the scorpion. Antares is the heart of the scorpion; perhaps you can see the stars that form the scorpion’s long curved tail. Scorpius is one of the few constellations, or star groups, that looks something like you thing it should. North of Antares is a bright star-like object, not as bright as Jupiter, this is Saturn. Venus will dominate t early morning eastern sky. Venus is the third brightest natural object in the sky after the Sun and the Moon.
You should be able to easily spot three bright stars which form a large triangle. Since the triangle is visible all night long during the Summer up north, it is called the Summer Triangle. Each bright star marks a different star group or constellation. Farthest West and lowest in the sky is Vega, part of Lyra the Harp. To the South is Altair, in Aquila the Eagle. The third bright star is Deneb, marking the tail of Cygnus, the Swan. Perhaps you can see other stars which form the Swan’s body, neck and head and its wings which spread wide. Cygnus is flying South along the Milky Way. The Milky Way looks like a hazy band of light arcing across the sky. It is the light from billions and billions of stars so far away, that all we see is their light combined into this haze.
From time-to-time the Earth passes through a cloud of dust left behind by a comet and you can see a meteor shower. The dark clear skies of the Virgin Islands make the islands a great place to see these “shooting stars”. About fifty miles above the Earth, walnut size pieces of dust and ice are passing through the air so quickly that they burn up and you see a flash of light, a shooting star. The flash happens so quickly that if you say to a friend “look over there”, by the time they look the flash will be gone. July, August, and October all bring meteor showers.
The Delta Aquarids is an average shower that can produce up to 20 meteors per hour at its peak on the night of July 29th to the morning of July 30th.
In the early morning hours of August 12th you will be able to see the Persid meteor shower, the best meteor shower of the year. The comet which left the dust behind which forms the Persids is comet Swift-Tuttle. Swift- Tuttle was discovered in 1862. It was found again in 1992 and astronomers have since found records of it going back to 69 BC.
The Orionids is an average shower producing up to 20 meteors per hour at its peak. It is produced by dust grains left behind by comet Halley, which has been known and observed since ancient times. The shower peaks this year on the morning of October 22nd.
On August 21st there will be a solar eclipse as the Moon will come directly between the Earth and the Sun. From the northern Pacific Ocean, across much of the United States, and out into the Atlantic Ocean the Moon will completely block out the Sun and people will experience a Total Solar Eclipse. In USVI the Moon will only partially cover the Sun: the partial eclipse begins at 2:14 pm, the maximum of the eclipse is at 3:36 pm, and the partial eclipse ends at 4:47 pm. It is important to never look directly at the Sun without proper eye protection. Sunglasses are NOT proper eye protection.
The Sun will shine directly overhead on the equator on September 22nd and there will be nearly equal amounts of day and night throughout the world. This is the first day of Fall (autumnal equinox) in the Northern Hemisphere and the first day of Spring (vernal equinox) in the Southern Hemisphere.