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When the temperature gets astronomical

With everyone's attention fixed on the thermometer, the scorching days we've had lately have inched their way into the record books.

Imagine the sun beating down at an unrelenting 109 degrees — and then some. Not bad for a star that is 93 million miles away. Calculating for the speed of light which is about 186,000 miles a second, the sun's rays take about 8 minutes to reach us.

Mercifully, our planet isn't closer to the heat-radiating center of our solar system. Imagine what it must be like for the folks on Venus or Mercury who are the much closer to the sun. (If there aren't any folks on either of those planets, it just might be because they're toast).

Mercury is the closest planet to the sun in our solar system so you would expect it to be the hottest. But the surface temperature of Venus is actually higher. And we're talking a lot more blistering than Medford was this week. It can get to 882 degrees Fahrenheit on Venus and 806 degrees on Mercury.

The big difference is that on Mercury all you have to do is wait until nightfall and the temperature will drop to as low as -297 degrees. Of course, you'll have a bit of a wait. A day on Mercury lasts 176 Earth days.

There's virtually no atmosphere on Mercury. When the sun's rays hit the planet, they stay there. Mercury gets 6.5 times as much sunlight as we do on the Earth and the sun shines 11 times hotter on Mercury than it does on Earth.

If you should be so foolish as to look at the sun from Mercury it would be about 21/2; times bigger than it appears from Earth. And instead of the sun floating in a beautiful robin's-egg blue sky, seen from atmosphere-less Mercury, the sky is black, just they way it looks to the astronauts from the space shuttle.

When you add it all up, Mercury experiences the greatest extremes of temperature of any place in the solar system. If it's any consolation, there is no humidity on Mercury. That's what people say about Las Vegas but it doesn't make it feel any cooler there.

Meanwhile, even though Venus is twice as far from the Sun and receives 25 percent as much sunlight, it is not only hotter than Mercury, it's one of the hottest places in the solar system.

Venus is surrounded by thick clouds of mostly carbon dioxide, with some nitrogen, carbon monoxide, argon, sulfur dioxide, and water vapor.

Once the infrared energy from the sun gets inside Venus' atmosphere, it can't get out. Just like in a greenhouse, where the windows have been painted to keep the sun's energy trapped inside. A smaller version of the greenhouse effect takes place in your car when you leave the windows up on a hot day.

On Venus, things heat up to the point where surface temperatures get high enough to melt lead. But once again, because of the Las Vegas effect, there is almost no relative humidity once you reach the surface.

The United States and Russia sent space probes to Venus hoping they would land on the surface. After spending an hour in Venus' atmosphere the probes stopped working and were presumed to have melted.

One day on Venus equals 117 earth days. Venus rotates in the opposite direction from earth. That means that, viewed from Venus, the Sun rises in the west and sets in the east.

This would make it difficult to stage "Romeo and Juliet" on Venus, even though it is the planet of love. Romeo stands beneath Juliet's window and says: "But soft! What light through you window breaks? It is the east, and Juliet is the sun!"? But if he's comparing his lady love to the rising sun on Venus, Romeo would have to say: "It is the west, and Juliet is the sun!"

If you want to check out these two celestial hot spots — Mercury and Venus, not Romeo and Juliet — both planets just happen to be visible in the sky lately.

Mercury can hard to see but it is very close to the west north-west horizon just after sunset. Venus is the morning star and is the bright light you see in the east about an hour before sunrise.

So, when it gets to be 100 degrees down here on Earth, remember it's eight times as hot up there on Mercury and Venus — and be grateful.