Gopal Pathak Karkhedkar

तृतीयं भूग्रहणं कमलाकरोक्तम्

होलिकादहन रात्रौ पश्येमः एको नरश्वानः , १०००अब्द्यन्तरे मानवस्वरूपम्।

Comet Pons-Brooks' Ion Tail (APOD: 2024 Mar 26)
Image Credit & License: James Peirce
https://apod.nasa.gov/apod/ap240326.html

Explanation: Comet Pons-Brooks has quite a tail to tell. First discovered in 1385, this erupting dirty snowball loops back into our inner Solar System every 71 years and, this time, is starting to put on a show for deep camera exposures. In the featured picture, the light blue stream is the ion tail which consists of charged molecules pushed away from the comet's nucleus by the solar wind. The ion tail, shaped by the Sun's wind and the comet's core's rotation, always points away from the Sun. Comet 12P/Pons–Brooks is now visible with binoculars in the early evening sky toward the northwest, moving perceptibly from night to night. The frequently flaring comet is expected to continue to brighten, on the average, and may even become visible with the unaided eye -- during the day -- to those in the path of totality of the coming solar eclipse on April 8.

https://creativecommons.org/licenses/by-nc-nd/2.0/
https://www.flickr.com/photos/jamespeirce/

Starship Asterisk* • APOD Discussion Page
https://asterisk.apod.com/discuss_apod.php?date=240326

How to find the North Star It's easy to find Polaris, the North Star, in the night sky, using the Plough asterism as a guide to help you locate it.

Physics Term of the Day (20/01/2024)

Moon Phase Calendar for the month of January, 2024😍
Credits: Calendar-12.com

Happy Perihelion Day! On Perihelion Day, the earth is closest to the sun in its elliptical orbit. Today, the earth is about 5 million kilometers closer to the sun than the usual average.

१४ अक्टूबर २०२३ तारिखायां सूर्यग्रहणस्य क्रमिकस्थितयाः

This is a composite recording the sequence around mid-eclipse of the October 14, 2023 annular eclipse of the Sun. At this eclipse the Moon was near apogee so its disk was not large enough to completely cover the Sun's photosphere and create a total eclipse.

This is a blend of 8 exposures each taken 2.25 minutes apart, about the minimum time to keep the disks separate and avoid them overlapping. The set flanks mid-eclipse, but an image taken at mid-eclipse is not included as annularity at this site lasted 3m03s, so I chose to include frames taken near the start and end of annularity showing the Moon almost tangent to the Sun.

The sequence starts about 6 minutes before the start of annularity and ends about 6 minutes after annularity concluded. The centre two frames show annularity (the Moon's disk framed completely within the Sun), while the frames on either side show the partial phases before and after.

The time sequence runs from left to right, with the Sun in the morning sky rising up and moving across the frame to the upper right. However, the Moon itself was moving slowly down across the disk of the Sun, a motion due to its orbit around the Earth, which carried it across the Sun moving down from frame to frame.

The camera did not move or track the Sun. I started the sequence with the Sun at lower left and let it move across the frame.

As such, the composite is a natural blend of frames positioned by the motion of the sky, not by an arbitrary placement in Photoshop. This is how the Sun and Moon moved during the time around mid-eclipse, as seen from my site near Bryce Canyon National Park at the Ruby's Inn Rim Overlook. This site was well south of the centreline, so the Moon moved across the top of the Sun and was not centred on the Sun at mid-eclipse.

This is a subset of frames selected from 300+ taken every 4 seconds, using a Canon RF100-400mm lens at 400mm and at f/8 for 1/60-second exposures at ISO 100 with the Canon R camera. The lens had a 67mm threaded Seymour Solar glass filter on it. Some high cirrus cloud added a bit of haze around the first Sun. But overall, the sky this morning was superb.