Tag Archives: Sun

How can I safely look at the Sun?

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 Update 5 June 2010: In less than a year, this article is already out of date.  First, NASA’s STEREO satellites have been supplanted by SDO as the ultimate solar observatory, and it’s gorgeous high resolution images of the Sun currently dominate astronomy image galleries.  Second, the Sun’s unusually long dormant period finally ended – there is now usually plenty for solar observers to see.  And finally, I am no longer observing for ASSA‘s solar section – personal commitments have not … Continue reading →

How far away is the Sun?

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Earth orbits the Sun at an average distance of 149,598,000 kilometers.  Astronomers refer to this distance as 1 Astronomical Unit (AU), which is a handy unit for measuring distances within the Solar System.  But the actual distance changes every day, because the Earth’s orbit is elliptical and not perfectly circular.  On the 3rd of January each year, Earth is at its closest point to the Sun, with a distance of 147,098,074 km.  It is at its furthest point (152,097,701 km) on … Continue reading →

Solar Eclipse

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As the Earth revolves around the Sun, and the Moon revolves around the Earth, it happens sometimes that all three fall into alignment.  When this happens at New Moon, the Moon covers up the Sun in our skies, and we have a Solar Eclipse.  It is an interesting coincidence that both the Moon and the Sun appear to be the same size in the sky, since both their actual sizes and their distances from earth are radically different, but this … Continue reading →