The Sun will undergo a Partial Eclipse on Thursday June 10^th beginning at 11:14 with maximum eclipse visible at 11:46 am, however do not get too excited. The Sun will only have a very small portion eclipsed from Valencia Region, approximately 1.1% and this will not cause any noticeable reduction in light output. To be able to observe the event a telescope equipped with a special Solar filter will be required to ensure the intense light of the Sun is safely reduced. Never attempt to view the Sun through any optical aid as it is extremely dangerous and will cause blindness or very serios eye damage.

During the first day of June, look for the Last Quarter Moon close to Jupiter in the pre-dawn sky. In the evening, as dusk begins on 11^th and 12^th look to the NW, the Crescent Moon will be close to the brilliant planet Venus, with the added bonus of the bright stars Castor and Pollux, also Mars being close by. Although Mars is now receding away from us it is still easily seen and noticeable by its distinct orange hue. On the evening of 19^th the Moon will be close to the bright star Spica, the leading star of Virgo. Here in the UK daylight lingers later and during mid-June there are no truly dark night time skies as we reach the Summer Solstice. From the UK it is possible to notice Noctilucent (Night Shining) Clouds appearing in the Northern part of the sky after midnight, just as the brighter stars become visible, however at the lower latitude of Spain are rarely noticed. Noctilucent clouds appear wispy, like cirrus clouds however, they are silvery blue-white in colour and contrast well with our normal atmospheric clouds which appear dark. Noctilucent clouds reflect the Sun’s light as they are at very high altitudes, typically 80km. The clouds form from water vapour which attaches to tiny dust particles within the extremely low temperature region of our upper atmosphere, the Mesosphere. The tiny dust particles are possibly from volcanic activity or from incoming micro meteors. Noctilucent clouds are only normally visible within latitudes 45° to 80° N and equivalent in the Southern hemisphere and surprisingly have only been reliably recorded since 1885. It is not surprising that observations of these clouds began after the catastrophic eruptions of Krakatoa and Augustine volcanoes of that year. The Krakatoa eruption was devastating, it ejected massive amounts of volcanic ash into the upper atmosphere and killed 36,000 people. The eruptions of Krakatoa and Augustine were however preceded by other volcanic activity including Mount St. Helen’s in 1800, Tambora in 1815 and Shiveluch in 1854, all of which released large volumes of volcanic ash particles into the upper atmosphere.

Studies of the Noctilucent clouds undertaken by Russian astronomers V K Tseraskii and A A Belopolskii in 1885 found that Noctilucent Clouds are formed at 73 – 83 km above the Earth’s surface. Particles which form the clouds are in the order of 30 – 100 nm radius. Most researchers conclude that prior to the 1883 Krakatoa eruption there is no evidence of observations of Noctilucent clouds. The British artist Robert Leslie noted strange sightings of clouds late on the Summer evenings of 1884 however his handwritten descriptions are not conclusive as he may have witnessed clouds of ejected volcanic material as his descriptions give the clouds a violet and purple hint.

If you do manage to spot these elusive clouds, they are very easily photographed using a smartphone and they really do contrast well against the darker sky. Take care enjoy the night sky. 

astronomy@u3aoliva.org