Sunday, May 16, 2010

May 16, 2010: Crescent Moon and Planet Venus

Above is an actual view of the moon about 7:00+ P.M May 16, 2010 in Bicol, Pili, Camarines Sur...

Photos courtesy of:
Blesilda Bascara-Livelo (facebook)

About 10 hours Universal Time today. Unfortunately, this is not visible to North American or European observers, but we have not lost out entirely. Tonight, just as it gets dark, look to the western sky and, weather permitting, you should see a beautiful sight — bright Venus with the waxing crescent moon nearby. You should have no trouble finding either object as long as your skies are clear and you are facing west. Venus is a brilliant beacon to the lower right of the moon. Look early, as the two set less than three hours after the sun. By the way, the moon is currently said to be “waxing” in the sense that it is becoming a bit more full each evening.

If you are a regular reader of EarthSky Tonight, you may have noticed over the years that we have reported passages of the crescent moon near Venus several times. In fact, it is not that unusual. The moon passes somewhere near Venus about once a month, although we don’t always mention it simply because the conditions for observing are not always favorable. However, what you have not ever seen is a mention of the quarter moon, or gibbous moon, or full moon passing near Venus. Yet, we sometimes report when these phases of the moon pass near Mars, Jupiter and Saturn. So why is it that only the crescent moon ever passes Venus?

That is because Venus is “inferior.” No, I don’t mean that it is less valuable in any way. Used in this context, “inferior” means “lower than.” Venus is “lower than” the Earth relative to the sun. In other words, Venus is closer to the sun. Because of this, Venus never appears very far away from the sun in Earth’s sky. It oscillates back and forth from one side of the sun to the other, much like a race car moving from the left side to the right side of a circular track as we watch it from the stands. Thus, Venus sometimes appears in the evening twilight, and sometimes in the dawn twilight. The point is that it is never far from the sun. The farthest it can get from the sun (called an “elongation”) is slightly more than 47 degrees. Therefore, when the moon appears to pass Venus, it does so at about the same elongation from the sun. Since 47 and fewer degrees correspond to a crescent phase, only the crescent moon can appear to pass near Venus in the sky. The quarter moon is 90 degrees from the sun, and the full moon is 180 degrees, so you will never see those phases near Venus.

Mercury is an inferior planet as well, but its maximum elongation is only 28 degrees, so only a very thin crescent moon can ever appear near Mercury. On the other hand, Mars, Jupiter and Saturn are farther from the sun than Earth, making them “superior.” From time to time, they can appear at any angle from the sun, and the quarter or full moon phases can pass near them (sometimes even occulting them).

Written by Larry Sessions

Thursday, January 7, 2010

Android Phones

Nexus One is here
Posted on: January 5, 2010 / Category: Android News

We knew and expected this day for almost a month now: the Nexus One is finally available. We won't bother you with much details now, which seems to be the fashion amongst tech blogs, that have multiple posts covering the release of the Nexus. Instead we'll point you to the official site where you can see the specks, pictures and even buy the phone if you want:

Xperia X10 VS Motorola DROID
Posted on: December 16, 2009 / Category: Sony Ericsson Android Phones

This is a battle of giants, basically the best two Android phones face eachother (at least until the Nexus One crashes the party). I bet when Xperia X10 will come out it will be hard to chose between it and the Motorola DROID that's why a good comparisson is needed.

HTC Legend
Posted on: December 14, 2009 / Category: HTC Android Phones

It's not hard from the picture above that the Legend is actually the HTC Hero 2. Some big improvements expect the Hero fans, like metalic frame, AMOLED display, optical mouse, LED flash and a 600MHz processor.

Motorola Titanium
Posted on: December 14, 2009 / Category: Motorola Android Phones

Another Motorola Android phone emerges: the Zeppelin we saw in the leaked roadmap a while ago is heading for China Mobile, under the name XT800, at least initially. That's interesting but we are more interested if it comes to US or Worldwide. And it looks it will.

Nexus One Pictures
Posted on: December 14, 2009 / Category: HTC Android Phones

The folks at Engadget managed to get hold of some new, more detailed pictures of the so called "Google Phone" better known as Nexus One. Beside the pictures we have some more informations on the phone.

HTC Nexus One
Posted on: December 13, 2009 / Category: HTC Android Phones

If you followed the Android news lately you might have noticed rumors of an actual Google Phone, developed by HTC for Google, network unlocked, large screen and high specs. The phone was distributed yesterday to Google employees for intensive testing and many shared the news on Twitter.