APOD: Asteroids Near Earth (2011 Oct 01)

[APOD Robot]

Asteroids Near Earth

Explanation: Though the sizes are not to scale, the Sun and planets of the inner solar system are shown in this illustration, where each red dot represents an asteroid. New results from NEOWISE, the infrared asteroid hunting portion of the WISE mission, are shown on the left compared to old population projections of mid-size or larger near-Earth asteroids from surveys at visible wavelengths. And the good news is, NEOWISE observations estimate there are 40 percent fewer near-Earth asteroids that are larger than 100 meters (330 feet), than indicated by visible light searches. Based on infrared imaging, the NEOWISE results are more accurate as well. Heated by the Sun, asteroids of the same size radiate the same amount of infrared light, but can reflect very different amounts of visible sunlight depending on how shiny their surface is, or their surface albedo. That effect can bias surveys based on optical observations. NEOWISE results reduce the estimated number of mid-size near-Earth asteroids from about 35,000 to 19,500, but the majority still remain undiscovered.

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[Beyond]

Space Freckles

[bystander]

NASA Space Telescope Finds Fewer Asteroids Near Earth
CfA: http://www.cfa.harvard.edu/news/2011/pr201126.html
JPL: http://www.jpl.nasa.gov/news/news.cfm?release=2011-304
WISE: http://wise.ssl.berkeley.edu/sciupdates_neowise.html

[twc]

Does this image represent only asteroids found in the orbital plane of the earth? Wouldn't a two dimensional image representing a three dimensional space show some higher densities toward the center of the image, assuming that the gravitational effect of the sun would draw them into a spherical shape?

[orin stepanek]

Wow!and they took away Pluto's planetary status because it hasn't cleared out it's orbital path. Looks to me like Mercury; Venus; Earth; and Mars hasn't either.

[MrsDK]

Orin Stepanek, Resident Geezer, voiced my initial thought quite well. If one really applies the "cleared out its orbital path" criterion, how many planets does Sol have?

[zbvhs]

Would these be the source of phenomena like gegenschein or is that something different?

[neufer]

Would these be the source of phenomena like gegenschein or is that something different?

<<Zodiacal light is produced by sunlight reflecting off dust particles in the solar system known as cosmic dust. Consequently, its spectrum is the same as the solar spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the solar system, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The gegenschein may be because particles directly opposite the sun as seen from Earth would be in full phase.

The Poynting-Robertson effect causes the particles to spiral slowly into the Sun, thus requiring a continuous source of new particles to maintain the zodiacal cloud. Cometary dust and dust generated by collisions among the asteroids are believed to be mostly responsible for the maintenance of the dust cloud producing the zodiacal light and the gegenschein. In recent years, observations by a variety of spacecraft have shown significant structure in the zodiacal light including dust bands associated with debris from particular asteroid families and several cometary trails.>>

[daverne]

Am I correct in assuming that this illustration is saying there are roughly 20,000 asteroids larger than 100 meters, that are located in the orbital plane between the sun and before the asteroid belt between Mars and Jupiter?

[drollere]

point of english usage: "light" is *visible* electromagnetic radiation. the standard of light is the human eye and the radiation it can detect in most situations.

it is incorrect to use the phrase "infrared light" for the same reason it's incorrect to use the terms "xray light" or "microwave light" or "heat light". i understand the desire to celebrate the photon, but photons are not light.

the wavelength range of the human eye is roughly 750 nm to 380 nm. it would be interesting to know the wavelength detection range of the satellite survey instrument. with the muddle created by "infrared light", it's impossible to draw any conclusions.

[Chris Peterson]

Does this image represent only asteroids found in the orbital plane of the earth? Wouldn't a two dimensional image representing a three dimensional space show some higher densities toward the center of the image, assuming that the gravitational effect of the sun would draw them into a spherical shape?

Asteroids are essentially ecliptic objects- they have low inclinations. There are only a very small percentage of asteroids which have been perturbed into high inclination orbits. There is nothing the Sun can do that will have that effect- asteroids near the Sun lie on the ecliptic just as ones far from the Sun do.

[Chris Peterson]

Wow!and they took away Pluto's planetary status because it hasn't cleared out it's orbital path. Looks to me like Mercury; Venus; Earth; and Mars hasn't either. :mrgreen:

It's a bit of an illusion- the scale of the drawing makes it impossible to see that the Earth's path is clear, as are the paths of the other inner planets. There is a broad swath around all the planets that is largely clear of other material (the same is true for Pluto, as it happens).

[Chris Peterson]

point of english usage: "light" is *visible* electromagnetic radiation. the standard of light is the human eye and the radiation it can detect in most situations.

Not so. "Light" is a broad term with many definitions. It can quite properly refer to any electromagnetic radiation, or to only visible EM, or to EM that lies within a wavelength range where optical principles apply for analysis, detection, and control. That latter definition is probably the most commonly used in astronomy and physics.

Very few people working in optics would consider IR (even far IR) or UV anything other than "light".

[neufer]

"Light" is a broad term with many definitions.

• ...

Light, n. [OE.light, liht, AS. leót; akin to OS. lioht, D. & G. licht, OHG. lioht, Goth. liuhap, Icel. ljs, L. lux light, lucere to shine, Gr. white, Skr. ruc to shine. . Cf. Lucid, Lunar, Luminous, Lynx.]

<<Light beer is beer that is reduced in alcohol content or in calories, compared to regular beer. The spelling "lite beer" is also commonly used. Light beers may be chosen by beer drinkers who wish to manage their alcohol consumption or their calorie intake. However, these beers are sometimes criticized for being less flavorful than full-strength beers, being "watered down" (whether in perception or in fact), and thus advertising campaigns for light beers generally advertise their retention of flavor.

In Australia, regular beers have approximately 5% ABV; reduced-alcohol beers have 2.2%–3.2%.
In Canada, a reduced-alcohol beer contains 2.6%–4.0% ABV, and an “extra-light” beer contains less than 2.5% ABV.
In Scotland, beers were taxed according to strength in the 19th century. The weakest category, 60/-, was generally under 3.5% ABV.

In the United States, most reduced-alcohol beers, including Bud Light, Coors Light, and Miller Lite have 4.2% ABV. This is a 16% reduction in alcohol compared to beer that has 5% ABV. Also, some establishments are permitted to sell only reduced-alcohol beer. For example, in Colorado, Kansas, Minnesota, Oklahoma, and Utah, beer that is sold in supermarkets and convenience stores must have no more than 3.2% alcohol by weight (4% ABV). This low-alcohol beer is called "low-point beer" or "three-two beer". Minnesota has a full-service alcohol license that is available to retailers. It permits the sale of regular beer, but licenses permitting the sale of 3.2% beers are easier to obtain.

"Light beer" can also refer to beer that has a reduced calorie content, compared to regular beer. Reducing the calorie content of beer is done by a large reduction of its carbohydrate content and a small reduction of its alcohol content. Most beer of this kind is not significantly less intoxicating than regular beer, although Budweiser Select is labelled as having under 3.2% ABW, possibly to permit its sale in localities that have 3.2% beer laws. Beer Advocate suggests it actually contains 2.5% ABV, or 50% of the alcohol in a normal American-style non-light lager.

The calorie content of beers varies over a wide range:

• Bud Light contains 110 calories per 12-ounce serving.
  Coors Light contains 102 calories.
  Miller Lite contains 96 calories.>>

[Chris Peterson]

<<Light beer is beer that is reduced in alcohol content or in calories, compared to regular beer...

I strongly disagree that "light beer" is beer. While "light" is frequently rendered "lite" in this case, it is actually "beer" that should be altered... to "byr" perhaps. In the U.S. at least, you can't use the term "cream" unless there is actually dairy cream in the product- otherwise "creme" is typically used. "Light beer" is false advertising, pure and simple, and undeserving of that historical term!

[NoelC]

This strikes me as the kind of thing that would be better expressed as a video, with a 3D "flyover" showing where all these asteroids are, and maybe even animated to show their motion.

'Course that might scare the hell out of folks (me included).

-Noel

[Beyond]

This strikes me as the kind of thing that would be better expressed as a video, with a 3D "flyover" showing where all these asteroids are, and maybe even animated to show their motion.

'Course that might scare the hell out of folks (me included).

-Noel

In that case, a lite byr just wouldn't do. You'd need the full effects of a light beer, to get through the experience FAST

[neufer]

<<Light beer is beer that is reduced in alcohol content or in calories, compared to regular beer...

I strongly disagree that "light beer" is beer. While "light" is frequently rendered "lite" in this case, it is actually "beer" that should be altered... to "byr" perhaps. In the U.S. at least, you can't use the term "cream" unless there is actually dairy cream in the product- otherwise "creme" is typically used. "Light beer" is false advertising, pure and simple, and undeserving of that historical term!

Very few people working at Coors brewery would consider Coors Light anything other than "beer."

Coors brewery in Golden, Colorado

---

<<The Coors Brewing Company managed to survive Prohibition relatively intact. Years before the Volstead Act went into effect nationwide, Adolph Coors with sons Adolph Jr., Grover, and Herman established the Adolph Coors Brewing and Manufacturing Company, which included Herold Porcelain and other ventures. The brewery itself was converted into a malted milk and near beer production facility. Coors sold much of the malted milk to the Mars candy company for the production of confection. Manna, the company's non-alcoholic beer replacement, was a near beer which is similar to current non-alcoholic beverages. However, Coors and sons relied heavily on the porcelain company as well as a cement and real estate company to keep the Coors Brewing Company afloat. By 1933, after the end of Prohibition, the Coors brewery was one of only a handful of breweries that survived Prohibition intact.

All the non-brewery assets of the Adolph Coors Company were spun off between 1989 and 1992; the descendant of the original Herold Porcelain ceramics business continues to operate as CoorsTek.>>

[Chris Peterson]

Very few people working at Coors brewery would consider Coors Light anything other than "beer."

Ignorance, I say, pure and simple ignorance!

(I often drive past the Coors brewery heading up to the Colorado School of Mines in Golden, and I can tell you, it doesn't even smell like a proper brewery.)

[Beyond]

...it doesn't even smell like a proper brewery.

And That's bad

[Chris Peterson]

...it doesn't even smell like a proper brewery.

And That's bad :?: :?:

Bakeries and breweries... two things that should (and usually do) smell wonderful.

[orin stepanek]

I like a beer now and then; especially the amber and dark beers you can get at the mini breweries.

[NoelC]

Typical. People drinking themselves into ignorance of the threat of asteroid collisions. Great idea!

Don't they brew non-light beer up in Golden? Certainly there are Coors varieties other than Coors Light, and some of them quite good. If so, how would what the brewery smells like be pertinent to a discussion about whether they brew a Light variety?

-Noel

[bystander]

Killian's Irish Red is a pretty good beer for an American commercial brew.

[owlice]

There is no such thing as a "good beer" for an American commercial brew!