Tag: comets

Comet 2019Y4 4/7/20

Update on C/2019Y4  April 7, 2020

(See all updates by clicking on the comets icon at the top of my home page)

Readers may remember that I wrote about this comet:

“As it nears the sun, it will brighten quickly.  It could become the brightest object in the sky.  However, it may just break apart and disappear.  See the text on figure  1 at This link

So, you were warned – and that last part may well be happening now.  Below is a collection of all photometric (CCD) observations of Comet 2019Y4 from March 7.  Below that is a graph of the distance from the comet to the Sun (orange) and from the comet to Earth (blue) for the same period.  The distances are in Astronomical Units – the distance from the Earth  to the Sun – about 93 Million miles

You see that:

* The comet was brightening until about April first.  Then it declined rapidly until today April 7th.

* In that time, it has gotten closer to the sun, which illuminates the comet better than before and closer to the Earth – where we should see it brighter than before – even without the additional illumination by the Sun.

* See the Conclusions below  the charts

  • One expects a comet to lose mass as it is blown away by the solar wind – that is what makes the “tail”. That would cause a dimming due to a smaller reflective surface and smaller “gas ball” surrounding.  This will be offset by brightening by being nearer to the Sun and Earth.
  • In this case, the dimming is faster than the brightening due to being nearer. The comet is probably wasting away quickly – on its way to disappearing for good.
  • But, I could be wrong. 🙂
  • Hasta Luego, Steve

P.S. If you have any questions please use the comments section (Leave a Reply) below and I will answer for all the readers who may have had the same question. Thanks SBC

Comet 2019Y4 April 3

April 3, 2020 – update on Comet 2019Y4

The weather has been even worse than usual for astronomy.  Don’t misunderstand – around here, there are just awful conditions for viewing at the best of times.  But cloudy weather has been unusually frequent lately.  The comet is still not very bright, in an area of the sky that is devoid of any bright stars for guidance and in a direction that is particularly afflicted with trees and city-light.  Nevertheless, I have attempted to spot the comet with binoculars several times – without success.

Attempting to photograph what could not be seen visually of Comet 2019 Y4, I am struggling with an unfamiliar DSLR (digital single lens reflex) camera.   Just the camera on a tripod and guessing at various settings of exposure, “film” speed, focus and aperture.  No, I didn’t see the comet.  I was barely able to detect any stars in the city-light washed-out sky.

One thing that stood out was some much more concentrated and colorful points of light.  I wondered what these could be since they were far to point-like to be anything in the sky that was not even properly focused.  Despite that these were intense and focused bits of light.

Figure 1: In the blue circle, a star. Doubt me if you must, but it is there – about half the diameter of that blue circle. In the red circle, an unexplained cluster of bright pixels

Figure 2: Zooming on a longer exposure frame, this is a star, blurred by incompetent focus and unstable air.

The bright spot in the red circle  of figure 1 – what could make such undeniable point-like events?  The answer came back – after considerable snaky-eyed concentration – these must be traces of cosmic rays.  As it turns out – I was right.  The lens of the camera has nothing to do with these images.  The high-energy particles pass through the camera body from any and all directions.  If at a low angle to the “chip”,  the image extends to an oblong shape, like the examples below.

Figure 3. Left: the example of a cosmic ray trace in a DSLR camera at the website found by googling cosmic rays. Right: Extreme zoom, on what I found on my DSLR during my attempts to photograph the comet.

The irony is that the comet, which is right here in the Solar System – along with stars that are in the visible “neighborhood” are so elusive, while cosmic rays, which may originate half-way across the universe, are showing up  clearly as “volunteers”

It has become clear that I will have to make a trip out to a dark sky location to see this comet.  That may take a while, so I will hone my skills with the binoculars and camera, in the meantime.

 Others are not so unfortunate in their efforts to see this comet. Collected observations of the comet show that it has dimmed in the last week.  Please see figure 4.

Figure 4. It can be seen that the brightness fluctuates, but is in a down trend in the last few days.

Hasta Luego,



Comet 2019 Y4

Comets show up all the time and are observed by telescope. The rarity is of “naked eye visible” comets. My personal experience is that they show up about once per decade (click here).

I was due for another comet and it has shown up.

Figure 1.

The media are incorrectly calling it “Comet Atlas”. Search for that name and about three dozen comets will pop up because ATLAS is the acronym for the name of the observing system that discovered it, not that of the comet itself. The Asteroid Terrestrial-impact Last Alert System is – as the name reveals – a project to find asteroids. It does occasionally discover a comet and it finds thousands of supernovas – in other galaxies – none are even close to “naked-eye objects”.

As most nerdy people know, comets frequently defy prediction and disappoint millions of viewers. Thus far, Comet 2019 Y4 has only defied prediction by rapidly brightening far in excess of prediction. Please see graphic below.

Figure 2. Note that “Magnitude” goes to smaller numbers as things get brighter.

The green line plots the predicted brightness. Points in blue are from actual observations. Note that this comet has grown to near naked eye visibility (from a dark sky, not in city lights).

Where to see this? A screen grab of a sky map from Heavens-Above.com for 3/25 to 3/27 (with text and markings by your humble narrator to “Un-nerd” same) appears below.

Figure 3.

Update: I tried, unsuccessfully, to see this comet with binoculars – in glaringly lit-up Houston skies on March 24. The latest brightness observed (by professionals) is Mag. 7.6 as of 3/25. But, it will get brighter, soon.

Update: No luck on the 25th, either.

An up-to-date sky map for locating Comet 2019 Y4 is here.

That Heavens-Above.com map is at the link below:

Hasta Luego,