Bob Moler's Ephemeris Blog

This is Ephemeris for Tuesday, March 22nd. Today the Sun will be up for 12 hours and 15 minutes, setting at 7:57, and it will rise tomorrow at 7:40. The Moon, 3 days before last quarter, will rise at 1:34 tomorrow morning.

Last week, NASA and the Space Telescope Science Institute (STScI) released a photograph of the star they had been using to align the mirrors of the James Webb Space Telescope. What started a couple of months ago as a scattering of in and out of focus images of that star, are now coalesced into a single image. The six spikes on the very overexposed star are called diffraction spikes, caused by the straight edges of the hexagonal mirrors. The other objects in the field are distant galaxies. So even this calibration image appears to meet or exceed expectations. There is more work to be done in getting the other three instruments that will receive light from the telescope aligned and calibrated. We’re probably two months away from the first scientific image.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

The alignment image of the James Webb Space Telescope after the 18 primary mirror segments have been aligned to act as a single mirror. Beside the alignment star showing its overexposed diffraction spikes, many faint galaxies can be seen. The alignment star, near the Big Dipper, is almost too faint to be seen in binoculars. Credit: NASA, Space Telescope Science Institute (STScI).