Starship Asterisk*

Bet a capacitor on one of the circuit boards went kablooye and shorted out. had one do that when I was working in my previous life and put a hole the size of a dollar on the board. Someday, man will actually get to Mars, and no doubt the wreckage and/or remains of all the probes will be forensicall...

I was wondering about the density of stars in globular clusters, like M13, or near the Milky Way's center. While the mass of individual stars has much to do with it, how close can typical stars be packed before they begin deforming and tearing at one or another?

Remember Pathfinder (1999?) only lasted 3 months. IIRC, Pathfinder was the delivery and communications relay vehicle while Sojourner was the robot vehicle. The mission was to have lasted one month, but continued for three months. Pathfinder failed I think for reasons still unknown, not necessarily ...

aichip,

I much appreciate the detailed and factual response. Thank you.

APOD for February 4, 2007, shows the shadow of the Opportunity Rover on Mars. I was wondering what percent of the Martian days does the sun cast a shadow. Are there many cloudy days on Mars, and if so, what are the clouds made of that obscure the sun? By what mechanism do these clouds form? Mars is ...

It's probably a typo ... It certainly turned out to be a typo, but not in APOD. I simply use this forum to inquire about any astronomical topic, not necessarily those in APOD itself. I went back to the original neutrino detector article, and I found ellipses (...) in the Antarctica Sun post (see ht...

Regarding neutrino detectors in Antarctica, in the following excerpt from http://www.spaceref.com/news/viewnews.nl.html?id=1172 : "We're looking at as much of the ice as we can see at one time, which works out Ö to be about 10 to 15 percent of the whole continent. We're able to see neutrinos in...

Please refer to http://spaceflightnow.com/news/n0611/18ulysses/

WRT the orbit of the Ulysses spacecraft, what two parts of the zodiac is it aligned with, and does the satellite precess along the zodiac?

the second half of my reply. I have a NIKON D70 and a 1000 mm lens attachment. What filter to use to take a photo of the sun ( I admit I know a lot of stuff but I am a rookie at astro pictures- noone evers lets out how they took the pictures that appear on APOD ) I've been thinking about your desir...

Nereid wrote:... and quintessence a value other than -1.

Other than -1, but still negative, correct? Quintessence and sign aside, why is w or Λ an integer?

It is (represented by Λ); w is a parameter in the equation of state. ... Did you read the wikipedia page to which I provided a link? Yes and no. Yes, I did read it. No, I did not understand it (both the article and the equation of state). To my knowledge, Quintessence is something originally postul...

Nereid wrote:... Einstein's cosmological constant is w = -1. ...

Whoa! I thought the CC was represented by Λ. If its value is now -1 due to the accelerating universe, was it a) +1 when the universe was thought to be static and b) zero when the universe was found to be expanding?

... Basically, a hypothetical force introduced by Einstein into GR that had no basis in observation seems to have been realized by an observable force called dark energy. ... I don't think Einstein introduced anything of the kind. I believe his equations naturally led to an expanding universe, and ...

the second half of my reply. I have a NIKON D70 and a 1000 mm lens attachment. What filter to use to take a photo of the sun ( I admit I know a lot of stuff but I am a rookie at astro pictures- noone evers lets out how they took the pictures that appear on APOD ) ta, It would probably be better for...

I'm confused about the cosmological constant (CC, Λ). I assumed Einstein only included Λ to correct his General Theory of Relativity because the prevailing view at the time was that the universe was static. I thought Λ was later removed (completely) only when Hubble showed the universe was actually ...

Why was so much attention and scientific instrumentation, in space and on earth, devoted to the recent transit of Mercury (or for Venus for that matter)? Granted it was an infrequent event, but to my mind, it was only slightly more relevant than a lunar eclipse. What new science was sought and/or un...

Nereid wrote:Physics Forums would likely meet your needs ...

Nereid,

Physicsforums.com looks very promising, and I thank you for bringing it to my attention.

harry wrote:Many obejects out there are much much older and the known universe is not expanding and so forth.

Harry, which objects are older than 13.7 by?

From the AIP, Physics News Update #794 carried this item: ELLIPSOIDAL UNIVERSE. A new theoretical assessment of data taken by the Wilkinson Microwave Anisotropy Probe (WMAP) suggests that the universe---at least that part of it that can be observed---is not spherically symmetric, but more like an el...

What has the most recent observations and research uncovered about The Great Attractor, that spot in the universe where most observable galaxies seemed to be heading?

You have valid points and may apply somewhere, being more an exception that a standard, note that the voids of space are far from empty. If our sun didn't support a heliospere, the amount of new matter (which can be calculated by the static pressure limiting the size of the heliosphere), a BH would...

I was keeping the concept simple, It is highly unlikely that a BH would not have some matter orbiting, thus an accretion disk (using the term loosely) even if it is not as visible as the consuming of another star. I have always wondered what might exist in the great voids between the sheets of gala...

Leonard Susskind, in his book The Cosmic Landscape, wrote the following, p 325: We can only look on helplessly as the heat engulfs you. Soon your precious body fluids will begin to boil and then vaporize. It will become so hot the veiy atoms of your being will be torn apart. But it is foretold that ...

... for the original there is the original paper by Michelson at http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1920ApJ....51..257M&data_type=PDF_HIGH&type=PRINTER&filetype=.pdf For complete articles, how current is the ADS database? I have often wanted recent copies of A...

In 1919, Michelson and Pease used an interferometer on the 100-inch Mt. Wilson telescope to measure the diameter of the star alpha Orionis (Betelgeuse). See for example http://planetquest.jpl.nasa.gov/technology/michelson.cfm I do not understand how this device actually enabled the measurement of th...