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Mercury in the Morning

March 14, 2014

The irritating little planet Mercury just peeks into view over the next few days. Although it’s quite bright, it’s also quite low in the east as twilight begins to paint the dawn sky, so it’s tough to find. In fact, if you’re at high northern latitudes you might not be able to see it at all. The view gets better as you move farther south.

Mercury is the closest planet to the Sun. That makes it irritating to casual skywatchers because it never strays far from the Sun in our sky.

That also makes it irritating to the pros. Mercury is small — only about half-again the size of the Moon — and it’s almost always awash in the glow of twilight. The combination makes it difficult to see anything on its surface even with a telescope. And Hubble and other space telescopes don’t help much because they usually can’t point at anything that close to the Sun — the sunlight could fry their sensitive instruments.

That leaves a couple of alternatives. One is to use giant radio telescopes as radar systems — use them to bounce radio waves off Mercury’s surface and study the reflection. That technique has revealed likely deposits of ice near the planet’s poles.

The other alternative is to send a spacecraft to study the planet from close range. And so far, we’ve sent two. The first made its first close approach to Mercury 40 years ago this month — capturing the first good view of an intriguing but irritating little planet.


Script by Damond Benningfield, Copyright 2014

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