Comet C/2020 M3 (ATLAS)

Comet C/2020 M3 (ATLAS) was discovered on 27 June 2020. The acronym ATLAS stands for Asteroid Terrestrial-Impact Last Alert System, based on the Hawaiian islands. Two telescopes of the robotic early warning system are designed to detect smaller near-Earth objects a few weeks to days before they might impact Earth. Since 2017, the scopes survey one quarter of the observable sky four times each clear night. The system is NASA funded and operated by the University of Hawaii.

Orbits near the Earth of objects larger than 1 km are well-known. Most are well documented and predicted years in advance of their close approaches to Earth. Objects down to 140 meters in size are harder to see. It is estimated ⅓ of them have been found. None of those found so far are predicted to threaten Earth in the next century.

Smaller objects less than 140 meters are detected only when they are much closer to Earth. Late discovery means there is the greater potential for a locally catastrophic collision with little warning time if they are on a collision course. ATLAS looks for these smaller objects. Comet C/2020 M3 (ATLAS) was discovered by this system.

The comet became a popular object for amateur astronomers to image. By November 2020 it was nearing the Orion constellation. This image on 6 Nov 2020 was by José J. Chambó at his web site I thought it would be interesting to image this comet several times as it passed through Orion.

José Joaquín Chambó Bris

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Astro-Images | Centaurus-A

Centaurus-A is located in the southern hemisphere skies.  I have never seen it from my location 42˚ north latitude. It rises only 5˚ above my southern horizon in early December. I’m certain it is very familiar to my blogger friend Roger in Australia.  It is the 5th brightest galaxy and easily viewed by amateurs. It contains a black hole of 55 million solar masses ejecting jets of x-ray and radio wavelengths. Models suggest the galaxy collided with another smaller galaxy in the past leading to areas of star formation in the resulting complex structure. I enjoyed combining 3 greyscale Hubble images into this composite. In the center are several newly formed bluish stars. The dark areas are dust blocking the passage of light.

Centaurus-A | Hubble Legacy Archive | My Version


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Betelgeuse Dims in Orion

The star Betelgeuse has been in the news since December 2019. It is called a Red Giant due to its color and size. It is the upper left shoulder of Orion seen in this chart from Wikipedia Commons.

Orion_constellation_map.png: Torsten Bronger

It has a slight reddish hue visually and a diameter estimated to be nearly as large as the orbit of Jupiter. Betelgeuse is a variable star meaning its brightness changes over time. The time period is quite long on the order of 2000 days. In December 2019, variable star observers reported it had rapidly reached its lowest level ever observed. Speculation is widespread over whether it will soon become a Supernova. More on that later.

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Iridium Flare Pass | 2017 Dec 1

The Iridium 21 satellite passed over my part of Iowa this morning before sunrise. I set the iPad Air 2 on a firm base pointed at an angle toward the NNW sky. At 6:02 am, I started the 102 sec exposure using the NightCap Camera app, same as for the ISS pass three days earlier. The satellite was going north as it entered the frame at the top. After about 30 sec, a highly reflective mirror-like antenna cast a beam of sunlight down toward me. It brightened to several times more than the planets Venus or Jupiter ever get. Then it dimmed and continued north.

Taken with NightCap Camera | ISS mode | 102 sec | click to embiggen

Another satellite passed at the same time going toward the upper left from north-to-south. It is very faintly visible to the left of the flare. According to the Heavens Above database for my area, it was either a Russian satellite, or an Ariane rocket body.