Discontinued: This page was replaced on 22 Feb. 2012 by a new animated skychart on our home page.
Color coding: Objects in white
are outside ten lunar distances (LD) from Earth at the date-time indicated. Green
is for being inside ten LD, yellow
is inside Earth's "Hill sphere
" at less than 3.9 LD (except the Sun, of course), orange
is inside two LD, and red
is an intruder inside the Earth-Moon system at less than one LD from Earth.
These are screen shots from A/CC's prototype interactive sky chart viewer. Just glide your cursor over the date links at top to animate the chart images. No clicking is involved (but pausing the mouse over a date link will show object details in some browsers). The chart is centered horizontally on the opposition longtitude in front, and the Sun is split to each side behind. The phaseless Moon is obvious for its consistent motion of almost 13°/day.
The asteroids shown are those known to be within ten lunar distances (LD) of Earth or that have had very recent observation while on approach to, or departure from, a close passage. Asteroid motion is seen relative to Earth's own motion and appears faster when closer and slower when further away (sometimes seemingly stationary at this resolution). This sky chart takes a geocentric viewpoint and close objects may appear to be in different locations according to an observer's own viewpoint. Note that motion is increasingly distorted as an object moves away from the celestial equator and opposition longitude because spherical points are plotted here on a rectangular grid, such that the north and south poles have widths seemingly equal to the equator's length.
You may need to flush your Web browser's cache and reload this page to see the most recent chart images, and there may be a delay while the images reload.
This page's creator had long sought a way to do simple animation of large mixed-format images within Web pages and thought a little tip buried in CSS: The Missing Manual
, by David Sawyer McFarland, might hint at a solution. It pointed to a site that led in turn to Eric Meyer's Pure CSS Popups 2
page, which contains the clues needed to design the page you see here. Feel free to examine the HTML/CSS code for this page and to adapt the technique for your own purposes.
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