You can almost lose your way here, so take your time. A neutral density filter will help to tone down the light and make it easier on the eye. Look closely at the craters within and just beyond the dark collar several days before or after full Moon; their floors and walls display narrow, linear gouges that trace the blast tracks of impact debris across the region. What a sight it must have been in the day. Lunar erosion scratches away details relatively slowly, allowing us to appreciate the magnitude of the bombardment to this day.
Tycho's rays form a web of white spokes that extend up to 2, km across the lunar nearside, even as far as Mare Serenitatis, where the Apollo 17 astronauts collected their crucial sample. One possible ray bisects the mare and reaches even further, but it's still unclear if it belongs to Tycho or the crater Bessel , which it overlaps.
The rays aren't equally distributed but form a butterfly pattern with most extending to the lunar east, south, and northwest. Very few reach west, indicating that the projectile approached at a low angle from the west to create the off-center ballistic pattern.
A short, bright ray to the south-southwest of Tycho doesn't fit the pattern: instead of pointing back to the crater, it's nearly tangent to it. I've tried hard to imagine what might have happened in the chaos of impact to cause a stream of boulders to turn askew and land in such a non-radial fashion, but I'm still at a loss.
Was it redirected after colliding with another ejecta stream? Unrelated to Tycho? A remarkable pair of rays to the crater's northwest upper left run parallel, like the ruts cut by an the old wagon trains across the prairie. These features and others will be in full view this week during full Moon. But wait, there's more. With two full Moons this month the next falls on March 31st , we'll get to see it all over again!
I've wondered about that tangent ray that goes toward the lunar southwest from Tycho. The point where the tangent ray and the double ray would intersect is just about on the lunar western edge of Tycho. I can imagine the asteroid coming in from the west at a low angle, kicking up the debris that formed the tangent ray and the double ray, and continuing to plow into the lunar surface and excavate the crater.
But that's just a layperson's imagination. I hope the selenologists will figure it out and create a cool animation of the impact. Log in to Reply. Bob King Post Author. Anthony, It's an interesting idea. Studying the crater or looking at the photos it seems plausible.
Another possibility might be that the asteroid fractured en route and a fragment fell short of Tycho to create those rays. That's an interesting thought, too. What would make the asteroid fracture? There's no atmosphere to heat it up and create a bow shock. If the asteroid was loosely bound and spinning, I suppose a tidal interaction could pull it apart Although not the largest crater on the moon, Tycho is one of the brightest, indicating that it is one of the youngest of the craters.
It is the point of origin of a huge system of rays which encircle the moon, best seen in about a week when the moon is full. Tycho is 53 miles 86 kilometers in diameter with classic central peak and terraced walls. Editor's note: If you have an amazing skywatching photo you'd like to share it with Space. Catch it as the first gleam of sunlight strikes it, and watch the slow emergence of the central peak; then come the rays, so that by the time of the full Moon, everything is swamped in the pool of light.
For advice on capturing a lunar image, read our guides on how to photograph the Moon and how to draw the Moon. And get to know the lunar calendar with our guide to the phases of the Moon. To get weekly lunar phases delivered directly to your email inbox, sign up to the BBC Sky at Night Magazine newsletter. Crater Tycho, as seen by the Hubble Space Telescope. Yorkshire, UK. Equipment: Orion Starshoot IV. Equipment: Orion Planetary Camera, Skywatcher mm achromatic refractor.
Equipment: Skywatcher pds reflector, Orion Planetary Camera. The always amazing Tycho!
0コメント