Updates for the week ending: Sunday, September 27th
This summary is published every Monday, and is a list of SL viewer / client releases (official and TPV) made during the previous week. When reading it, please note:
It is based on my Current Viewer Releases Page, a list of all Second Life viewers and clients that are in popular use (and of which I am aware), and which are recognised as adhering to the TPV Policy. This page includes comprehensive links to download pages, blog notes, release notes, etc., as well as links to any / all reviews of specific viewers / clients made within this blog
By its nature, this summary presented here will always be in arrears, please refer to the Current Viewer Release Page for more up-to-date information.
The night of Sunday 27th / Monday 28th September promises a very special astronomical event for those fortunate enough to have clear skies overhead and are willing to stay up late (in the UK and Europe). It will see a total lunar eclipse take place at the time when the Moon reaches perigee, its closest approach to Earth in its orbit and giving rise to both a so-called “supermoon” and a “Blood Moon”.
A “supermoon” occurs when a full moon coincides with the time when the Moon is nearing its minimum distance to Earth, a distance of roughly 363,000 kilometres (226,875 miles), leading to it appearing 7-8% larger than when seen as a full Moon at other points in its orbit. A “blood moon” is the result of the Earth’s atmosphere, lying between the Sun and Moon, scatter blue light more strongly than red, so the latter reaches the Moon more strongly, giving it a reddish-brown colour when seen from Earth.
Lunar eclipses are not that rare – this one will be the second of 2015, for example. However, “supermoons” are somewhat rarer. The last was in 1982, and the next will not be until 2033. So, if you want to see a really big blood moon, and you live in Western Europe, West Africa, the Eastern side of the USA and Canada or south America, then the 27th / 28th September is the night to do so. People further afield – eastern Asia, the middle east, eastern Europe and the western sides of Canada, the USA and South America will see a partial eclipse.
In the UK, the period of eclipse will start at around 01:00 BST (00:00 GMT) on the morning of Monday, 28th September, and run through until around 05:00 BST (04:00 GMT). That’s from 20:00 through to around 01:00 EDT in the USA / Canada, and 02:00 through 06:00 CET in Europe).
The eclipse brings to a close what is referred to as a “tetrad” of total lunar eclipses – that is, four occurring “back-to-back”, with no partial eclipses between them, the first of which occurred in April 2014 and the “middle two” in October 2014 and April 2015. Some have a misguided view that this “tetrad” as being of particular significance because such events are “rare”, and this particular one started on the Passover.
However, while there can be long periods of time between occurrences of tetrads, they can also pop-up relatively frequently. For example, this century will see a total of nine tetrads occur, the first having taken place in 2003/4. Nor is the fact that this particular series started on the Passover particularly unusual; there have been eight tetrads so far coinciding with Passover since the first century AD.
So, if you are in a position to see the eclipse, you can leave the tinfoil hat on the table and step outside quite safely. Totality should occur around two hours after the eclipse starts (e.g. 03:00 BST in the UK / 04:00 CET, 22:00 EDT on the 27th September), and that’s the best time to enjoy the blood moon in all its glory.
The eclipse will also give NASA the chance to measure the full range of temperature variations during such an event. This will be done by the Lunar Reconnaissance Orbiter (LRO), a solar-power vehicle which has been observing the Moon since 2009.
Normally during an eclipse, the LRO has most of its systems powered down to reduce the load placed on the battery systems. However, mission controllers are confident they will be able to run an instrument which will allow it to accurately measure the amount of heat loss the surface of the Moon experiences when inside the Earth’s shadow, further helping them to understand the composition of the Moon’s regolith and its function as an insulator.