A Springtime Collection of Comets

“The Hour arrived—and it became
A wandering mass of shapeless flame,
A pathless Comet, and a curse,
The menace of the Universe!”

Lord Byron, “Seventh spirit” from the dramatic poem Manfred, 1817.

Throughout history and across cultures comets have be viewed with dread, fear, and awe. They have been branded with such titles as “the Harbinger of Doom” and “the Menace of the Universe“. Nowadays, we look forward to observing them and hope for a comet bright enough to view with our naked eyes.

Comet C/2019 Y4 Atlas from Cqoutilam on April 14, 2020.
Comet C/2019 Y4 Atlas imaged from Coquitlam BC on April 14, 2020

This spring features a fine collection of bright comets. It is doubtful that any will reach naked-eye visibility so a small telescope or binoculars are recommended for observing them.

A comet’s brightness is measured on a scale called visual or apparent magnitude. The following table is a refresher on some common magnitudes for those not familiar with this scale. Notice the scale is backwards where small magnitude indicates brighter objects.

ObjectMagnitude
Venus (brightest planet)-4.6
Sirius (brightest star)-1.4
Polaris (the North Star)2.0
Naked-eye limit (city/urban)
Faintest star seen from a city location
3.0
Naked-eye limit (dark sky)6.0
Binocular limit9.0
Small Telescope limit (100 mm refractor)11.0

C/2019 Y4 Atlas

C/2019 Y4 Atlas had stargazers looking forward with anticipation to the next great naked-eye comet. Its rapid brightening in Feb 2020 led to speculation that it would become a naked-eye comet that might even be visible in daylight.

“a comet may be visible with the naked eye in late April and early May. It’s even possible that it could get bright enough that it’s visible at twilight while the sun is still up”

Thrillist: https://www.thrillist.com/news/nation/comet-atlas-c19-y4-headed-near-earth-2020

But it was a bit of a let down to learn that images taken in early April showed its nucleus starting to disintegrate.

This image, taken on April 20, 2020, shows fragments of C/2019 Y4 (ATLAS). Image credit: Quanzhi Ye & Man-To Hui.
An image taken on April 20, 2020, shows fragments of C/2019 Y4 ATLAS. Image credit: Quanzhi Ye & Man-To Hui

C/2019 Y4 Atlas is still relatively bright at magnitude 9.5 and is in a good position for viewing. It appears about 30° above the horizon in the northwest at 11 pm. It is headed lower and dimming so the next few weeks may be our last chance to observe it.

Graph showing correlation between the brightness of C/2019 Y4 Atlas and BC's COVID-19 cases.
Correlation between the brightness curve of C/2019 Y4 Atlas and BC’s COVID-19 cases

With tongue in cheek, one can see “evidence” that comet C/2019 Y4 Atlas was a “harbringer of doom”: It appeared and started to rapidly brighten just before the number of cases of COVID-19 in BC started to ramp up; The comet’s peak brightness corresponds closely with the peak of COVID-19 cases; and The curves for the comet’s brightness and the number of new COVID-19 cases have both shown signs of flattening. Perhaps its recent dimming should be interpreted as a foreshadowing that the worst of COVID-19 is over 😉

C/2020 F8 SWAN

Comet C/2020 F8 SWAN may be the brightest comet of 2020 – if you able to observe it from the southern hemisphere. It is already bright at 7.0 mag and is expected to brighten to magnitude 3.5 as it continues to approach the Sun during May.

Comet C/2020 F8 Swan
Comet C/2020 F8 Swan with its striking ion tail. Featured as the APOD on April 29th, 2020 . Image Credit: Gerald Rhemann

It has developed a striking tail. In the Northern Hemisphere, it is only visible extremely low in the sky in late May. It will re-appear in the morning sky in August but by then is expected to have dimmed down to mag 11.

C/2017 T2 PanSTARRS

The comet C/2017 T2 PanSTARRS has been a steady performer. It became brighter than mag 10 on New Year’s Day 2020 and is currently at magnitude 8.2 as it makes its way from Camelopardalis toward the Big Dipper. It reaches perihelion, its closest point the Sun, on May 4th.

Comet C/2017 T2 PanSTARRS
Movement of Comet C/2017 T2 PanSTARRS on Nov 20th, 2019 from Coquitlam, BC.

It is expected to be at its maximum brightness of 8.0 on May 15th. For a special treat, a few days later on the nights of May 22nd and 23rd, the comet will pass within 2° of the galaxies M81 and M82. It should remain bright until July and is well-positioned for viewing from Vancouver during the next few months.

Chart for C/2017 T2 PanSTARRS close to Bode's Galaxy M81 on May 22 at 23:00
From Vancouver C/2017 T2 PanSTARRS will appear close to Bode’s Galaxy M81 & the cigar galaxy M82 on May 22 at 11:00 pm

On June 4th, the comet will be easy to find as it passes less than 1° from Dubhe, the brightest star in the Big Dipper.

C/2020 Y1 Atlas

Another comet that is well positioned for observing from Vancouver is C/2020 Y1 Atlas. It is following a similar path to C/2017 T2 PanSTARRS, heading higher in Northern sky.

Comet C/2019 Y1 Atlas
Comet C/2019 Y1 Atlas on April 14th, 2020. Image credit: Roland Fichtl
Light Curve for Comet C/2019 Y1 Atlas
Observed and Predicted Light Curves for Comet C/2019 Y1 Atlas from http://astro.vanbuitenen.nl/comet/2019Y1

It is currently around 7.9 mag and has continued to brightening even though it reached perihelion on Mar 15. Its observed brightness has consistently being higher that the initial predictions as shown in its light curve where blue and black dots are visual and photometric CCD observations from COBS or the MPC, and the gray curve is based on the original MPEC or MPC predictions. Software like Stellarium and SkySafari appear to be displaying the magnitude for this comet from the initial predictions – as a result, the comet might appear much brighter in the sky than it does in the simulated views from the software.

Lets hope it stays bright longer as it will be within 0.5° of the Owl Nebula M97 and within 2° of the galaxy M108 on May 25 at 11:00 pm PDT as seen from Vancouver – that should make a nice photo op.

Chart for comet C/2019 Y1 Atlas near the Own Nebula M97
Stellarium Chart for C/2019 Y1 Atlas near the Owl Nebula M97 on May 25, 2020 at 11:00 pm as seen from Vancouver. The red circles have diameters of 0.5° and 2°.