Welcome to the July night sky. This is the month when the day time Sun really heats up and the night time temperatures can reach 30ºC here in southern Portugal.
Luckily this month is when the Earth is slightly further away from the Sun than average as the Earth’s orbit is slightly elliptical. The difference is only 3% but it serves to make our northern hemisphere summers a little less hot than they would otherwise be.
Due south, when the evening sky eventually gets dark enough, can be seen the constellation of Scorpius, and its brightest star is called Antares. This is a red giant star and is so large that it has over a million times the volume of our Sun but, as it is hundreds of light years away, it only appears as a star-like point in the sky in any telescope.
Red giant stars are at the end of their lives and Antares will eventually explode as a supernova sometime in the future. This could haappen any time from now or a
million years in the future but, when it does, it will shine brighter than
the full moon and be visible even in daylight for many weeks.
It’s been more than 500 years since a really bright supernova has been seen in the northern skies so we are overdue for one.
A little to the left of Scorpius, you will find the constellation of Sagittarius. In this region of the sky is located the centre of our Milky Way galaxy and on a dark moonless night, this area is full of countless faint stars.
Over in the southwest about 45 degrees above the horizon, the ringed planet Saturn is still visible in the constellation of Virgo. This planet is the only bright one visible
in the evening sky with the gas giant planet Jupiter only rising at 2am. Jupiter is close to the constellations of Pisces and Aries. The half Moon is below Saturn on the night of July 7.
Meteor shower
The Capricornid meteor shower is visible during the last week of July with many bright-yellow meteors. As with any meteor shower, they are best visible after midnight and this time there is no Moon in the sky, so any faint meteors will be easier to see.
This month we have two New Moons, one on July 1 (today) and the other on the 30th.
The Moon is new on the 1st, first quarter on the 8th, full on the 15th and last quarter on the 23rd and new again on the 30th of July.
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