[Achshar]

Brace yourselves: the doomsday articles/memes/stories are coming..

PS will it be visible to naked eye? if yes then when and where and for how long and where in the sky? can there be a real time Google earth 3d simulation like NASA did for space shuttle launch?

[brlewis]

The asteroid's surface is darker than charcoal at optical wavelengths. Amateur astronomers who want to get a glimpse at YU55 will need a telescope with an aperture of 6 inches (15 centimeters) or larger.

[lutorm]

Yeah, it's the low albedo that kills you. Something that large made of ice would probably be quite bright.

Quick OOM calc: This thing has an area proportional to the moon of (200m/1700km)^2. The moon has an albedo of ~0.12. An object with albedo 1 would thus have a brightness of ~1e-7 of the Moon's. The full Moon has a magnitude of -12.7, so such an object would have a magnitude of -12.7-2.5log10(1e-7), or about 4.8. That's clearly visible to the naked eye at a dark site, but not very impressive.

[Achshar]

hmm looks like i skipped that part :(

[nickpinkston]

Good question - an aircraft carrier nearer than the moon? I can't imagine that'd be visible to the naked eye - even ships on the horizon disappear pretty quick. Then again you can see satellites sometimes, but that's like 4 orders of magnitude closer.

[cbr]

Ships disappear on the horizon because of curvature, not distance.

[nickpinkston]

LOL - I know that... I mean well I look at them from line of sight (on a mountain) only 30 miles away they're little specs...

[Achshar]

well but if it comes when its night and it has a tail long enough and is also bright enough,and is close to moon from the perspective of someone on earth and hence moon light makes it more visible, then.. who knows??

[maaku]

Asteroids don't have tails.

[Achshar]

Its funny how here you get down voted for not reading a part of news thoroughly, or for that matter being wrong. (Or even for acknowledging that you were wrong), i am dying laughing here guys haha..! great work keep up..

EDIT: in case you couldn't fathom, that was sarcasm.

EDIT 2: seriously, stop it! or reply as to why are you down voting? is it a crime to mistakenly post a comment and then acknowledge your mistake or are you guys just some proud 'elite' HNers?

[udp]

General rule of thumb:

If you find yourself editing your post asking people not to downvote, it's time to delete it.

[Achshar]

"or reply as to why are you down voting?"

well i don't want to get upvotes but if you disagree with me then please take some more time to write a quick comment as to why.

Well i posted asking if it will be visible to naked eye, someone quoted a part of the story (indirectly) saying that it won't be and i happened to have missed that part, and i get down voted (for missing reading a part of the story).. well then i acknowledge that i missed it and i get down voted still even then i asked the down voter why was he is down voting my comments and guess what.. i got down voted.. again. but no one has balls to write back, or maybe they are super busy with their work but anyways, and i wont edit this comment but i can say two things:

- you (or any of the downvoters) probably won't reply to this comment either. - this comment will (almost certainly) be down voted too.

lets see how correct i am..

[knieveltech]

You worry entirely too much about karma.

[Achshar]

again.. i dont need karma, i am just saying that if someone disagrees with me, just comment and tell me why, so that we can discuss or i can know why am i wrong.

[udp]

You get downvoted when your comments are low quality and/or don't add to the discussion. Every comment you write with "why did you downvote me???" is both low quality and doesn't add to the discussion.

Relax, it's only HN. Go build something instead.