Stories tagged Venus

Dec
01
2008

Moon and planets #1
Moon and planets #1Courtesy Mark Ryan
When I was a kid I remember my dad would like to point out that the word "syzygy" was one of very few multi-syllabic words that didn't contain any of the "normal" vowels. Moon and planets #2
Moon and planets #2Courtesy Mark Ryan
The definition in an astronomical sense is when three or more celestial bodies in the same gravitational system line up in essentially a straight line. One example would be the Sun, Moon, and Earth during an eclipse. Another may be the phenomenon that was visible in the western sky just after dusk today. Moon and planets #3
Moon and planets #3Courtesy Makr Ryan
Here are four photographs I shot of the alignment of the Moon with the planets Jupiter and Venus. I don't know if the celestial alignment is technically a syzgy but the word has stuck with me and I'm still waiting to use it in a game of Scrabble.

Moon and planets #4
Moon and planets #4Courtesy Mark Ryan
PLEASE NOTE: From my vantage point the event was happening right in a flight path for the Minneapolis-St. Paul airport so aircraft kept flying through the frame. That's what all the streaks and extra lights in the photos are. The exposures were long, ranging between 6 and 15 seconds, and I used a timer so as not to shake the camera during each exposure. Timing the shutter with the aircraft was tricky but I got a few good ones.

Two of the brightest planets, Venus and Jupiter, appear very close together tonight. Tomorrow night (Dec 1) they will be joined by the crescent moon around 6 pm (CDT) to make an "unhappy face".

"This is set to be the best planetary gathering of the year, simply because it involves three of the brightest objects in the sky after the sun," said Geza Gyuk, director of astronomy at the Adler Planetarium in Chicago. National Geographic.

Nov
30
2007

Where's the lightning?: I can't see any lightning in this picture, but recent magnetic antenna data shows that Venus has regular lightning flashes in its dense atmosphere.
Where's the lightning?: I can't see any lightning in this picture, but recent magnetic antenna data shows that Venus has regular lightning flashes in its dense atmosphere.Courtesy NASA
With a name like Thor, any mention of lightning and thunder jumps off the page (or computer screen) demanding my immediate attention.

So I was locked into yesterday’s account that the European Space Agency’s Venus Express has confirmed the theories astronomers have had for years, that lightning strikes on Venus.

Lightning is one of the factors considered in the evoluntionary process that could have “sparked” life into inorganic materials. But weather and climate conditions on Venus today suggest that the window of supporting life forms has been long shut on the planet.

But the finding of lightning has electrified the weather forecasts for Earth’s solar system neighbor. Previously, astronomical meteorologists had figured that Venus had a long, boring forecast of strong, steady winds for the next 400 years.

Venus Express, which has been orbiting Venus for nearly two years now, used a magnetic antenna to pick up the planet’s lightning activities.

So if you had a strong enough telescope to see a lightning flash on Venus, how long would you have to count until you hear the ensuing thunder clap? Talk amongst yourselves to come up with the answer.

Jul
11
2007

Venus and Mars are alright tonight: They may not teach us much about conditions on Earth, but they provide hours of entertaining temperature conversion!  Photo of Venus (left) from NASA; photo of Mars (other guy) from the Library of Congress.
Venus and Mars are alright tonight: They may not teach us much about conditions on Earth, but they provide hours of entertaining temperature conversion! Photo of Venus (left) from NASA; photo of Mars (other guy) from the Library of Congress.

As Science Buzz's resident global warming skeptic, I've taken a lot of shots at Al Gore over the years. Today, however, I find myself in the unusual position of having to defend him against unfair attacks. Somewhat.

In an editorial last Sunday, Gore stated:

“Consider this tale of two planets. Earth and Venus are almost exactly the same size, and have almost exactly the same amount of carbon. The difference is that most of the carbon on Earth is in the ground - having been deposited there by various forms of life over the last 600 million years - and most of the carbon on Venus is in the atmosphere.

As a result, while the average temperature on Earth is a pleasant 59 degrees, the average temperature on Venus is 867 degrees. True, Venus is closer to the Sun than we are, but the fault is not in our star; Venus is three times hotter on average than Mercury, which is right next to the Sun. It's the carbon dioxide.”

This got a bunch of bloggers to thinking. George Reisman went to a NASA website and found an interesting comparison:

PLANET Venus Earth Mars
CO2 IN ATMOSPHERE 96% 0%* 95%
AVERAGE TEMPERATURE 867˚F 59˚F -81˚F

*Not quite true: Earth’s atmosphere is 0.035% CO2.

So, planets with lots of carbon in their atmosphere can be either broiling hot or icy cold.

(Another writer, Evan Kayne, complained (seventh item) the comparison isn't fair; Reisman didn’t take into account the fact that the atmosphere on Mars is only 1.3% as thick as Earth’s. James Taranto of the Wall Street Journal re-did the calculations, and concluded that frigid Mars still has 34x as much CO2 per cubic foot of atmosphere as the Earth does.)

So far, Al isn't looking too good. But then, blogger David Downing thought he'd discovered another problem. According to the NASA site, Mercury has an average temperature of 452˚ Kelvin, while Venus has an average temp of 726˚ Kelvin. That’s only 1.6 times hotter, a far cry from what Gore had claimed!

Wait a minute. What’s this “Kelvin” scale and why is Downing using it? Well, all temperature scales measure energy. And on the Kelvin scale, 0 degrees means “no energy AT ALL.”

This makes it very easy to compare the energy in different systems. In Celsius, 0 degrees doesn’t mean “zero energy;” it means “the amount of energy in frozen water” -- which may seem chilly to you and me, but at a molecular scale, it’s got plenty of heat. (0 degrees Fahrenheit is apparently the amount of energy in a mix of ice, water, and ammonium chloride.) Comparing 25˚F to 50˚F is tricky, because the scale doesn't stop at 0. As any Minnesotan knows, it goes wayyyyy lower than that!

(It’s kind of like saying “Mike is five years older than me; Vic is 10 years older than me; therefore, Vic is twice as old as Mike.” That would only be true if I were 0 years old. If I were, say, 47, then Mike would be 52 and Vic would be 57, and the differences would be much less impressive.)

So, Downing assumed Gore must have been working in Fahrenheit, and believed that if Venus is 867˚F and Mercury is 289˚F, then Venus is three times hotter. Ha ha, what a silly mistake! I was all prepared to poke fun at Al for this glaring error, until I realized – Mercury isn’t 289˚F. According to NASA, it’s a toasty 354˚F.

So, where did Al get 289˚F? I looked in a bunch of sources -- no one was even close. Wikipedia listed Mercury at a mere 26˚F. (The side facing the Sun broils; the side turned away freezes; this is an average.)

But then I noticed -- 26˚F is 270˚K. And Wikipedia lists Venus at 735˚K . Using the proper Kelvin scale, that works out to 2.7 times hotter than Mercury. Not quite 3 times, but in the ballpark. And, to be fair, Wikipedia gives Mercury a range of temperatures, and “3x hotter” fits comfortably within that range.

So, it turns out Gore was closer to being right than he’s given credit for. He WAS working in the proper Kelvin scale. He was just relying on figures from Wikipedia rather than from NASA.

I don’t know if all this has taught us anything about global warming. But man, have I learned a lot about planetary atmospheres, temperature scales, and math! Thanks, Al!

UPDATE: Evan Kaye had claimed that the atmosphere on Mars is only 2% as thick as Earth's. James Taranto, using figures from the NASA site linked to above, calculated that it is actually 1.3% as thick as Earth's. We have corrected the figure.

Apr
13
2006


Venus Express: Artist’s view of ESA's Venus Express probe in orbit around Venus. Image courtesy ESA - D. Ducros.

Another planetary probe has achieved orbit around a planet in our solar system. Much like NASA’s Mars Reconnaissance Orbiter, the European Space Agency’s (ESA) Venus Express entered an elongated orbit of Venus yesterday. The probe will spend the next four weeks to refine its orbit from its current 9 day to a 24 hour polar orbit.

The Venus Express was launched on November 9, 2005 and once it has reached its goal orbit will begin exploring the Venusian atmosphere. The probe will study the atmosphere’s complex dynamics and chemistry, as well as the relationship between the atmosphere and the planet’s surface, which will provide clues about surface characteristics.


Vortex: Atmospheric vortex over Venus' North pole. Image courtesy ESA - AOES Medialab.

One aspect of the Venusian atmosphere that Venus Express will investigate is the incredible atmospheric vortices that rotate over Venus’ poles. The vortex over the North Pole, has an unusual “double eye” configuration and its origin and impact on the planet continue to be a mystery.

This will be the fourth ESA probe to achieve orbit around another celestial body. The ESA also operates the Mars Express (Mars), SMART-1 (the Moon), and is NASA’s partner on the Cassini-Huygens orbiter (Saturn). The ESA is also operating the Rosetta probe which is on its way to the comet 67P/Churyumov-Gerasimenko, which it will begin orbiting in 2014.