Starship Asterisk*

Driven by the pressure of sunlight, its more diffuse yellowish dust tail is pushed outward and lags behind the comet's orbit. Is this correct? I thought the dust trail was material expelled from the nucleus and left behind, analogous to the smoke left behind a train. So the dust trail does lag behi...

Thank you -- that answers my question. I was just curious as to how these images would compare with what I could take with my own consumer-grade point-and-shoot camera if I were sitting inside New Horizons -- rubbing my hands over the plutonium RTG to keep warm.

A mission designed to place a probe in orbit around Pluto would certainly cost billions of dollars. So, what's wrong with that? The Iraq War, already 1000 days old when New Horizons launched, cost $1 billion per day for 3000+ days, and was, many believe, a mistake from day 1. Sorry to inject divisi...

Does anyone out there know the ISO equivalent speed or sensitivity of New Horizon's imaging sensor in visual light, and what exposure times are typical for the images we are seeing?

A few years ago, I was visiting Palm Springs, California. Late at night, I noticed a stationary bright point of light to the west about 15 degrees above the horizon. It was as bright as Venus, but Venus is never visible in the middle of the night. It did not move or change in any way during several ...

It appears that the brightly glowing central region has a far lower star density than the spiral arms. Is this just an artifact of image processing? Or have the innermost stars all been devoured?

The parameter z is the height above the picnic assuming a field of view of ~53º (i.e., 1 m 2 is observed at a height of 1m). In other words, z is the distance traveled at time t. I am with you so far. ...every thing is increasing exponentially from the microscopic to the macroscopic; the breaks at ...

Note: Velocity doesn't start at zero once the motion has actually begun; (it is more like 0.23 m/s). t = 10 log(z) z = 10 t/10 = e (ln(10)/10) t v = (ln(10)/10) z ~ 0.23 z a = (ln(10)/10) v ~ 0.23 v ~ (z/185) g's c ~ 3 x 10 8 ~ 0.23 z c z c ~ 1.3 x 10 9 meters t c ~ 10 log(1.3 x 10 9 ) = 91.14 seco...

I am bumping this thread in case anyone else has any comments. Many thanks to those who already replied.

In the first part of this movie, the side of the visible square starts at 1 meter at time t=0 seconds, and then increases by a factor of 10 every 10 seconds. For this to happen, our velocity away from the starting point must start at zero and then increase more and more rapidly. Questions: what form...

I wondered the same thing. Are the speckles just artifact, or are they actual particles reflecting light? Was the photo taken through a ring?

If we're merely looking for simple organic molecules on Mars, then I could have saved NASA $400 million -- there are some, just as there are simple hydrocarbons in Jupiter, Saturn, Titan, Uranus, Neptune, and in the ejectae from red giants and supernovae. I do not think we will find any unequivocal ...

If we're looking for ice, then why did we decide to land on red dirt again? Why didn't we aim for the bright, white, crusty stuff that we can see from Earth on the Martian poles?

The putative supermassive black hole at the center of our Milky Way is much too low in mass to exert gravitational influence on stars outside its nearby vicinity. So, if the Milky Way (and other spiral galaxies) are not whirling around a central black hole, then what are they whirling around? Why ar...

Let's say a new magnitude +18 object appears suddenly where nothing was visible before. Approximately how long would it take for someone to find it and report it? Hours? Days? Weeks? Do some parts of the sky receive better surveillance than others? If so, what would be the range of detection times f...

At first glance, I thought the black spot was a silhouette of one of Mars' small moons, orbiting below the Mars Orbiter. After excluding that possibility, I thought it must be an artifact or a deliberate fake. Since it doesn't appear to be either of those things, the mystery just gets deeper. If it ...

I'm enjoying the discussion, but I am still hoping to get an answer to one of my original questions: are distant quasars (>10 Gly) homogeneously distributed around Earth, or are they mostly in one direction, or scarce/absent in another direction? I am guessing the former.

rigelan wrote:Umm. The earth is the center of the universe.

Yes -- Earth is the center of the observable universe for an observer on Earth.

http://en.wikipedia.org/wiki/Observable_universe

This question was inspired vaguely and indirectly by today's APOD (3 May 2007). After searching the topic in this site and at Wikipedia, I am still puzzled. I understand that the "observable universe" is a perfect sphere, with Earth (assuming that is where the observer is located) at its c...