# How far away would a supernucleus comet be visible?

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If an instrument like LSST quickly spots something as soon as it reaches magnitude 24½, how far away would a 60km first-time visitor from the Oort cloud be when it is spotted? I'm thinking that a huge iceball will make a visible coma sooner, but have no idea what actual numbers would be.

And, given that distance and a parabolic orbit, how much time would that give before it crosses Earth's orbit?

Even 100 meter NEOs could cause significant damage, and there are far more of them. LSST will be able to detect objects as faint as 24.5 in magnitude in a 30s visit, enabling it to detect 140m NEOs as far away as the Main Belt asteroids. [… ] During its survey of the sky, LSST can find 90% of the PHAs over 140 meters in diameter.

Earth is 1 AU from the Sun, so that would be 1.2 to 2.2 AU away from us:

The Asteroid Belt is located in an area of space between the orbits of Mars and Jupiter. That places it between 2.2 and 3.2 astronomical units (AU) from the Sun. The belt is about 1 AU thick. The average distance between objects in the Asteroid Belt is quite large. If you could stand on an asteroid and look around, the next one would be too far away to see very well.

Timewise, it would be about 8 years away:

The bottom right panel shows an example of a very different hazardous object - the 3 km large comet C/1996 B2 Hyakutake, which passed within 0.10 AU from Earth in 1996. The apparent magnitude vs. distance diagram indicates that the current generation of wide-angle imaging surveys, such as SDSS with V < 22, could have provided an early warning about 3 years before the closest approach (if they had sufficient cadence and sky coverage). With LSST, the warning time would be ∼8 years, with over 500 observations over that period.

Fortunately, your comet is 60 km, making the comet tail easy to spot:

While the solid nucleus of comets is generally less than 50 km across, the coma may be larger than the Sun, and ion tails have been observed to extend 3.8 astronomical units (570 Gm; 350×106 mi).

This table of impact risks shows that the most likely (5.8e-02) impact is between 2095 and 2113.

## How to See Comet Iwamoto Fly Past Earth This Week

The brilliant, blue-green comet C/2018 Y1 Iwamoto will zip by Earth this week, and the speedy space "snowball" is currently visible in the night sky with binoculars and small telescopes.

Discovered just two months ago by amateur astronomer Masayuki Iwamoto, Comet Iwamoto is an icy body that orbits the sun in a highly elliptical path that takes 1,371 years to complete. After this encounter, the comet won't be back until the year 3390, so check it out while you can!

Comet Iwamoto will make its closest approach to planet Earth at a safe distance of 28 million miles (45 million kilometers) on Feb. 12, around 3:10 p.m. EST (2010 GMT), and it is currently racing through the solar system at a speed of approximately 148,000 mph (238,000 km/h) relative to Earth, according to NASA's Horizons database, which calculates the positions and velocities of orbiting bodies. [Photos: Spectacular Comet Views from Earth and Space]

Comet Iwamoto made its closest approach to the sun &mdash a point in its orbit known as perihelion &mdash on Feb. 7, when it swooped around our star at a distance of 26 million miles (42 million km). You can see Comet Iwamoto's path around the sun in the orbit animation above.

## Comets and how to view them

The popular image of a comet is one of a bright head with a long tail trailing behind it. You might remember comet Hale-Bopp during the spring of 1997, for example, which stayed in the evening sky for several weeks and was visible even from town centres. People sometimes make the mistake of expecting a comet to shoot across the sky. However, the only natural objects that shoot across the sky are meteors (shooting stars), which are caused by tiny particles from space being vaporised when they hit our atmosphere. Comets, on the other hand, only move slowly from night to night against the star background.

Comet Hale-Bopp, photographed in March 1997 from Devon, UK. Credit Robin Scagell/Galaxy

There are dozens of new comets discovered each year, but most only appear as faint fuzzy blobs when first detected, and often never get any more impressive. At the heart of each comet is what has been called a ‘dirty snowball’ – a chunk of ice usually just a few kilometres in size, orbiting the Sun. This is the source of the gas which could produce a tail. Being so small compared with a planet, this body, or nucleus, is too faint to be seen during the long intervals when it is far away from the Sun, as comets are generally in very elongated orbits rather than nearly circular ones.

However, when it approaches the inner Solar System, the warmth of the Sun causes some of the ice to evaporate from the surface of the comet’s nucleus. This forms a small haze or coma around the nucleus and makes the comet easier for astronomers to pick out against the star background.

As the comet gets closer to the Sun more material is ejected, causing the coma to expand and, in some cases, one or more tails will develop. One tail, the plasma tail, will contain the smaller gas molecules, whereas the other will contain heavier dust particles.

In contrast to the small size of the comet nucleus, these tails can be thousands or in some cases millions of kilometres in length. Due to the effect of the solar wind, the plasma tail will always point away from the Sun, though the dust tail may be more curved. Hence, on its way out from the Sun, the comet will travel tail first. The particles of the dust tail gradually spread around the orbit of the comet and, if they eventually encounter the Earth, will be vaporised as the shooting stars mentioned earlier.

But not every comet has a glorious tail. The vast majority remain as tiny, distant fuzzy blobs that don’t attract much attention. However, every so often a new comet turns up that comes closer to the Sun than most, and these are the ones that can become bright enough to be seen with binoculars or even the naked eye.

##### How bright will it be?

The first thing that the media will seize upon about a newly discovered bright comet is its predicted brightness. Rather inevitably, the media headlines will often only mention the most optimistic of the brightness predictions. The brightness measure usually quoted by astronomers is the total magnitude of the head of the comet. This is unfortunate because, although being a useful measure for scientists, it can be misleading for everyone else and can lead to disappointment. Because this ‘total’ brightness is spread out across a patch of sky, a comet of a particular brightness or magnitude will be less easy to see than a star of the same magnitude.

Nine months before its best appearance in 1997, Hale-Bopp was just a fuzzy blob seen in binoculars. Credit Robin Scagell/Galaxy

Movement of Comet Machholz over 48 mins. Credit Robin Scagell/Galaxy

This can be a particular problem when trying to spot a diffuse comet against a sky background that is hazy and/or suffers from light pollution. You also need to bear in mind that most comets are brightest at around the time of their closest approach to the Sun. At such times you may well find yourself having to locate the comet during twilight and/or low down in hazy skies. Consequently it may not be as spectacular visually as the magnitude predictions might have suggested. Even a bright star is hard to see in the evening twilight, and a comet of the same brightness is more spread out than a star, which is essentially a point of light.

##### Comet flops

In any case, the behaviour of comets is always difficult to predict. Back in 1973-4, comet Kohoutek was very much over-hyped in the media. Even though it did become a quite bright comet, it wasn’t the ‘greatest comet of all time’ that some media reports, based on the more optimistic magnitude predictions, had claimed it would be. In contrast, other less hyped comets have unexpectedly flared up in brightness and in some cases have broken up into two or more fragments.

##### Observing comets

For most comets – which are quite faint – you need a telescope, and really the bigger the better. Comets are very similar to deep-sky objects, particularly elliptical galaxies, in their appearance, with a fairly condensed nucleus and misty outer regions fading into the background. So the darker your skies the better you will be able to see the full extent. But while most comets are very small, one of the much rarer close or great comets can easily be so large that a telescope shows just the central condensation and only binoculars will show the full extent of the tail.

When first observing comets, you will probably be happy to merely locate the comet and follow its motion against the star background from night to night. After a while, you may find it rewarding to sketch the appearance of the comet, noting the direction and length of the tail, how condensed or diffuse the head of the comet is, plus the presence of any other notable features. Using averted vision will make it easier to see the fainter details. It is also useful to mark the positions of nearby stars. Remember, of course, to always record the instrument and magnification used for your observation. As for other types of observing, the more you observe comets, the easier you will find it to recognize detail.

##### Photographing a comet

If a comet is bright enough to be visible with binoculars, but maybe not easy to see in your sky because of light pollution, it may be possible to photograph it using a digital camera and a short time exposure. You’ll need to fix the camera firmly, usually on a tripod, use a telephoto setting pointing at where you know the comet to be, and give a time exposure of maybe 10 or 15 seconds. You’ll need to be able to control the camera settings, such as the focus (autofocus is useless where a dark sky is involved) and the sensitivity. Use a setting ISO 1600 or higher. Even many compact cameras will usually allow this, but you’ll need to read the instructions. Though the image may be faint on a single exposure, the trick is to add several images together in image editing software such as Photoshop.

Photographically, for faint comets you need the same set-up as for deep-sky photography, that is, an equatorially mounted telescope with some means of auto-guiding. However, while the auto-guiding would prevent deep sky objects from moving in the field of view, you’ll soon find that the comet has moved and you get a trail even if your star images are perfect. Auto-guiding on the comet isn’t usually feasible as the nucleus is not as bright and point-like as a star, so the auto-guider will have trouble. These days, it’s easier just to give short sub-exposures of around 30 seconds to a few minutes and add them afterwards.

More detailed observations will include measures such as the degree of condensation (DC) of the head (coma+nuclear condensation), the orientation and length of the tail and the integrated magnitude (m1). The DC value ranges from 0 = uniformly diffuse, through to 9 = star like. The orientation of the tail is measured as a position angle in degrees from north (000) through east (090). Estimating the magnitude of a comet is challenging, even for experienced observers. Various methods exist, all of which are based around defocusing so that the nearby comparison stars also become fuzzy in appearance.

With more experience, you may wish to submit your observations for use in detailed analyses. Further information regarding the required report content and format can be found at www.icq.eps.harvard.edu/ICQFormat.html.

A comet streaking across the sky, its tail stretching behind, is an amazing sight. Because comets are not visible all the time, they are usually special and even spectacular for people on Earth. In olden times, comets were considered as both good and bad omens. But what is a comet? Where do comets come from? And what is a comet made of?

A comet is basically a "dirty snowball" of dust and sometimes rock, frozen water, and frozen gases like ammonia, methane, carbon monoxide, and carbon dioxide. Comets travel in an orbit a short orbital-period comet is one that takes 200 years or less to go around the Sun, and a long orbital-period comet takes more than 200 years&mdashoften thousands or even millions of years. Halley's Comet is a short orbital-period comet that can be seen from Earth every 75 to 76 years. Comet Hale-Bopp, which was visible to the naked eye for 18 months spanning 1996 and 1997, is a long orbital-period comet that won't be visible from Earth again for several thousand years. Short orbital-period comets are thought to originate from the Kuiper Belt, while long orbital-period comets are believed to be from the Oort Cloud. The Kuiper Belt lies beyond the planet Neptune (between 30 astronomical units [AU] and 55 AU from the Sun), and the Oort Cloud, which is thought to be a spherical cloud surrounding the solar system, lies about 50,000 AU from the Sun. Objects in the Oort Cloud are made up of frozen water, frozen ammonia, and frozen methane.

Comets are made up of a nucleus, a coma, and a tail, as shown in Figure 1. A comet's nucleus can range from hundreds of meters to tens of kilometers across.

Figure 1. This simple diagram shows the different parts of a comet. (HEASARC, n.d.)

Occasionally, the gravitational influence of one of the outer planets or, in the case of the Oort Cloud, the gravitational influence of nearby stars, causes a comet to enter an elliptical orbit that carries it closer to the sun. The nucleus is volatile because it is made up of unstable matter that evaporates easily. As the comet orbits closer to the Sun, solar radiation&mdashthe energy that the sun gives out&mdashbegins to melt the nucleus and causes the volatile material and dust to come out. (We also feel solar radiation, in the form of sunlight, on our skin.) The dust surrounds the nucleus to form the coma. Solar winds push the melted material away from the nucleus, causing the tail to form. Some comas can be nearly a million kilometers wide while tails can be more than 100 million kilometers long. Later, when the comet moves away from the Sun to the outer solar system and beyond, the coma and tail disappear and the nucleus remains frozen. Figure 2 shows a comet as seen through a telescope. Sometimes, we can see comets from Earth without telescopes when they pass close to the Sun because their tails and comae reflect sunlight.

Figure 2. This color image of Comet C/2001 Q4 (NEAT) was taken at the WIYN 0.9-meter telescope at Kitt Peak National Observatory near Tucson, Ariz., on May 7, 2004. It is a composite picture, assembled by combining images taken through blue, green, and red filters. (T. Rector [University of Alaska Anchorage], Z. Levay and L. Frattare [Space Telescope Science Institute], and WIYN/NOAO/AURA/NSF)

As a comet travels towards the Sun, how does it melt? Do bigger comets melt faster than smaller comets? In this astronomy science project, you will model comets of different sizes and then use a hair dryer as a heat source (to mimic the Sun and other "warm" planetary objects) to determine how the size of a comet affects melting.

## Comet LoveJoy C/2014 Q2

This holiday we had a wonderful treat, Comet LoveJoy C/2014 Q2 made a wonder pass. Those int eh southern hemisphere had the best viewing and were able to come up with some amazing images. Unfortunately, I had to fight a horizon and some trees! Curse you trees! (Shakes fist at the trees.) As Always I like to provide a really good image so you know what you are looking at versus my image.

#### Comet LoveJoy Facts:

C/2014 Q2 (Lovejoy) is a long-period comet discovered on 17 August 2014 by Terry Lovejoy using a 0.2-meter (8 in) Schmidt–Cassegrain telescope. [1] It was discovered at apparent magnitude 15 in the southern constellation of Puppis. [1] It is the fifth comet discovered by Terry Lovejoy, means you need to look up the designations when looking for comet Lovejoy. . .you will see his others, you need to add the C/2014 Q2.

By December 2014 the comet had brightened to roughly magnitude 7.4, [4] making it a small telescope and binoculars target. By mid-December the comet was visible to the naked eye for experienced observers with dark skies and keen eyesight. [5] On 28−29 December 2014, the comet will pass 1/3° from globular cluster Messier 79. [6] In January 2015 it will brighten to roughly magnitude 4−5, [7] and will be one of the brightest comets located high in a dark sky in years. On 7 January 2015 the comet will pass 0.469 AU (70,200,000 km 43,600,000 mi) from Earth. [8] It crosses the celestial equator on 9 January 2015 becoming better seen from the northern hemisphere. [9] The comet will come to perihelion (closest approach to the Sun) on 30 January 2015 at a distance of 1.29 AU from the Sun. [2]

How fast is it flying? Currently as I write this it is traveling at 80,365.54 MPH, relative to the sun, or 129,335.85 KPH.(35.93 KM/s) You can find the live stream data here.

Before entering the planetary region (epoch 1950), C/2014 Q2 had an orbital period of about 11500 years. [3] After leaving the planetary region (epoch 2050), it will have an orbital period of about 8000 years. [3]

### Observing and Photographing:

Here is a photo that helped me find the comet:

image credits in the image

I took advantage of it being near stars and objects I could find. In the Northern hemisphere it was a bit more difficult to see. I can’t wait till after January 9th! (Plus I have my autoguider and will know how to use it by then so no more fuzzy bad tracking photos!)

If this doesn’t help you can always use the following website: http://theskylive.com/c2014q2-tracker I highly recommend storing that web page at least the main one here : http://theskylive.com/comets Put that in your tool chest to find these things!

To find it I looked on the night of 25December 2014, but couldn’t find it even using binoculars. I had been reading all over that you can see it but I couldn’t see a thing. I realized that these were all reports coming from the southern hemisphere. . . .its a bit different up north. weird saying that from Florida.

Even through a 6″ Schmidt–Cassegrain it was a tough find right now. That’s OK I am actually very excited to see this is goign to brighten up and put on an even better show for us in the northern hemisphere. When I took this the object was traveling at about 80,365.54 MPH, relative to the sun, or 129,335.85 KPH.(35.93 KM/s) and was approx 50 million miles from earth or 80.5million KM from earth. . . To find it I had good calm skies, and I had to star hop, I looked near Messier 79 and looked for it near star HIP 25273.

Comet Lovejoy (C/2014 Q2) taken by Me and my wife on 29Dec2014

How am I sure I got it? I mean it doesn’t’ have a tail. (It twice had it’s tail lost, most likely from solar winds.) [10] In the time frame starting at 11:43 PM (2343) Eastern time (GMT-5) 28Dec2014 , until 12:09 AM or 0009 29Dec2014, the object had moved. The following Photo is untouched and un edited I only adjusted levels enough for you to see it.

Yes it’s got blur and streaks from the motion of the Telescope tracking.

I inserted it to show the movement between the two, in the time frame of 26 minutes.

I am adding another photo of the Original with the star labeled.

Comet Lovejoy (C/2014 Q2) taken by Me and my wife on 28Dec2014 Near Star labeled.

Photo was a bit tough to post process. I could only adjust the levels and curves a bit to brighten up the image. Yes you can see it in the photo, but when the file saves the histogram has to be stretched in order to make it visible. There is a science behind it, I just don’t get it, other wise the image looks dark as can be. My Camera (Orion StarShoot G3 Deep Space Camera) likes to make things reddish or blue so I have to adjust the color to reflect what you see with your eyes.

If you can’t get to photo it, at least try to see it, you got some time, but See it before 2050. . . otherwise you gonna have to wait a bit!

## Comet NEOWISE Now Visible to the Unaided Eye

This image of C/2020 F3 (NEOWISE) was captured on July 09, 2020 by Raman Madhira at Ray’s Astrophotography Observatory. Image credit: Raysastrophotograhy / CC BY-SA 4.0.

C/2020 F3 (NEOWISE) is a retrograde comet discovered on March 27, 2020 by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission.

“In its discovery images, C/2020 F3 (NEOWISE) appeared as a glowing, fuzzy dot moving across the sky even when it was still pretty far away,” said NEOWISE principal investigator Dr. Amy Mainzer, an astronomer at the University of Arizona.

“As soon as we saw how close it would come to the Sun, we had hopes that it would put on a good show.”

C/2020 F3 (NEOWISE) captured on July 6, 2020, above the northeast horizon just before sunrise in Tucson, Arizona. Image credit: Vishnu Reddy.

“From its infrared signature, we can tell that C/2020 F3 (NEOWISE) is about 5 km (3 miles) across, and by combining the infrared data with visible-light images, we can tell that the comet’s nucleus is covered with sooty, dark particles left over from its formation near the birth of our Solar System 4.6 billion years ago,” added NEOWISE deputy principal investigator Dr. Joseph Masiero, a researcher at NASA’s Jet Propulsion Laboratory.

C/2020 F3 (NEOWISE) made its close approach to the Sun on July 3, 2020, and will cross outside Earth’s orbit on its way back to the outer parts of the Solar System by mid-August.

The comet will pass by Earth at a distance of 103 million km (64 million miles) while giving professional and amateur astronomers the opportunity to learn more about its composition and structure.

C/2020 F3 (NEOWISE) path across sky, stereographic projection. Image credit: Tom Ruen / CC BY-SA 4.0.

“People wishing to catch a glimpse of the glowing comet can spot it as it swings through the inner solar system, but its nearness to the Sun creates some observing challenges,” NASA astronomers said.

“For the next few days it will be visible about an hour before sunrise, close to the horizon in the northeastern sky in the United States.”

“Observers might be able to see the comet’s central core, or nucleus, with the naked eye in dark skies using binoculars will give viewers a good look at the fuzzy comet and its long, streaky tail.”

“As it speeds away from the Sun, C/2020 F3 (NEOWISE) will begin to make its appearance in the evening sky shortly after sunset on July 11, 2020.”

## Newly Discovered Comet Leonard May Provide a Sky Treat Later This Year

A newly discovered comet may provide us with a sky treat when it passes by Earth at the end of the year. In fact, it may even become the brightest comet of the year. Comet Leonard (or C/2021 A1) was first spotted on January 3 rd by astronomer Gregory J. Leonard at the Mount Lemmon Observatory in Arizona.

When it was first discovered, the comet was exceptionally dim with a magnitude of 19 (approximately 160,000 times dimmer than the faintest stars we see in the sky with the naked eye) but that was because it was close to Jupiter’s orbit of about 5 astronomical units (AU) from our sun (the distance of Earth to the sun is equal to one AU).

When the comet was first spotted, it was beginning to feel the effects of the sun’s rays and slowly started transforming out of its completely frozen state with some pictures even capturing what appeared to be a tail on it.

Since it has an exceptionally long, flat elliptical orbit that can bring the comet as far away as 3,500 AU from the sun, it isn’t a “new” comet that came from the Oort Cloud (those comets have never traveled near the sun before). Instead, it is believed that it actually flew past the sun on at least one occasion around 70,000 years ago. This means that it wouldn’t have “new” materials on its surface like frozen carbon dioxide, nitrogen, and carbon monoxide that would vaporize and end up not being as bright.

Based on how bright the comet currently is, it is believed that it will be bright enough by the year’s end to possibly be seen without any optical aid (maybe a brightness magnitude of 4).

Those who are willing to wake up a couple of hours before the sun rises, they’ll be able to see Comet Leonard in the lower portion of the east-northeast sky (traveling through the constellations Coma Berenices, Boötes and Serpens Caput) during the first two weeks of December. At that point, the comet will be visible with a small telescope or binoculars, and hopefully with the naked eye as well. It will make its closest approach to Earth on December 12 th at a distance of 21.7 million miles (34.9 million kilometers) from us.

In the second half of December, the comet will approach the sun so the light of dawn will obstruct our view of it therefore, the best time to see it would be in the very early morning hours from early to mid December. It will make its closest approach to the sun on January 3, 2022 at a distance of 57.2 million miles (92 million kilometers).

However, as we all know, comets can be unpredictable, but we’ll find out more information as the year goes on and Comet Leonard gets closer.

## Bringing the Universe to Classrooms and Homes around the World!

Just, beyond a galaxy - far, far away. lie, two other galaxies, in a galaxy group that, the three - have all to themselves. The little group is called the "Leo Triplet" but it is actually likely part of a larger group of galaxies called the "Leo-I" ('Leo One') group.

Moreover, like most things 'cosmological', the connections don't end there: gas-streamer bridges connecting one galaxy or group of galaxies to another group - ultimately, ending in "super-clusters" i.e., a cluster of clusters of galaxies - the largest, single structures in the universe!

The proximity of the Leo Triplet puts it roughly between our own "Local Group" of galaxies and the Leo-I group "galaxy-group neighbors", so to speak - or numerically: only, around 30-35mly (million light-years) distant. How far away is that? Well, about 300 times the diameter of the Milky Way galaxy, which is

 The "Leo Triplet" consisting of galaxies NGC 3628 (left), M65 (upper right), and M66 (lower right). Image provided by the author using Insight Observatory's 16" f/3.7 astrograph reflector, ATEO-1.

This tiny distant galaxy group features two spiral galaxies M-65 and M-66 discovered by French amateur astronomer Charles Messier a comet-hunter by avocation. He tallied a list of small, dim objects in the night sky that appeared to be comets but he soon found we're not as they didn't move from their positions over long periods of time. They were permanent entities. He kept this list only to avoid these objects in future comet searches which he performed in the years around 1773.

The third galaxy, NGC-3628, another spiral saw edge-on that is inclined 90° from our galactic perspective was discovered by German sister, and brother amateur astronomers William and Caroline Herschel back in the middle 1800s.

M-65, is a 'barless spiral, at 35mly. It is slightly warped, and, there has been some recent star birth activity in one of its gaseous H-II regions.

Of the three M-66 is closest at 31mly with a diameter of about 95kly. It is the brightest of the three but it is missing a large portion of one of its spiral arms. The missing mass from that arm was gravitationally removed by one or both of the other galaxies in the trio.

M-66, has a weak bar feature, extending from its core and in this way is reminiscent of our own barred-spiral galaxy, the Milky Way. As of 2018 five supernovae have been observed in M-66: SN-2016cok, 2009hd, 1997bs, SN-1989B, and 1973R. SN-1989B was discovered independently by amateur astronomers Mike Petrasko and Dale Alan Bryant - one, cold, still morning in Feb of that same year.

Lastly, NGC-3628, the edge-on galaxy in this trio is also known as the "hamburger" galaxy. (Yes - it does indeed look like a "quarter-pounder" - viewed from the side!) Its disk spans 90tly and sits at 35mly away. The galaxy is composed mostly of older stars and like the other two is easily visible in amateur-class telescopes (4+ inches of aperture diameter). NGC-3628 also sports a 300tly-long, 'tidal tail', connecting the other two galaxies. It is the most distant of the three at 35mly. Its disk is around 100tly across.

Since there has been so much supernovae activity within at least one of the galaxies in this trio, I've decided it would be a good idea to begin an extra-galactic supernova search program using these three 'island universes.

So, here's the plan: take images of the three galaxies all within a single frame at some periodic interval (time-series). Using an image of the three together that is known to be "supernova-free" - I can then compare subsequent images over time to the SN-free frame using a sort of 'blink comparator.

A blink-comparator is a device that was used frequently by astronomers to compare images of the same area of sky or objects within the same field-of-view of a telescope or camera over a specified interval. It involves the rapid sequencing back-and-forth of two images - one against the other. (In the distant, remote, ancient past - (*chuckle*: 1980's), I used two Kodak carousel slide projectors one stacked on the other projecting both slides at the same time onto a screen and then using a sheet of cardboard manually to alternately project the slide images one at a time in rapid succession onto the screen.

Currently, I'll use the two images in an animated, ".GIF", file, and "blink" them, that way. In this fashion, I can set the "blink" rate, interval, for optimal comparison. In this way, any deviation from the standard field (used as a sort of, 'control group'), such as blinking spot, line, or another anomaly, will stand out as extraneous data. This was how, Dr. Clyde W. Tombaugh, discovered the dwarf planet Pluto back in 1930. I'll be looking for any supernova activity within the three galaxies.

This is something that anyone using one of Insight Observatory's, remote telescopes can do on their own! It's a good way to involve oneself self in a Citizen Science project - of their own design!

I'll let you know if I find any action! -- you let me know what you find too!!

## How to photograph Comet NEOWISE: NASA tips for stargazers

Are you excited to spot Comet NEOWISE as it pops into view in the night sky? Do you want to try your hand at photographing the cosmic snowball? Let's take a look at some beginner astrophotography tips from NASA.

Comet NEOWISE, named for NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), the space telescope that first spotted the comet in March, is currently gracing our night skies with its icy presence. It made its closest approach to the sun on July 3 and the comet is now visible to skywatchers in the Northern Hemisphere. It is so bright that, while it can help to use binoculars or a small telescope, the comet and its tail are visible with the naked eye.

You can spot the comet in the night sky after sunset and in the northwest just under the Big Dipper constellation. For those who want to make those skywatching moments last a little bit longer, it can be fun to bring along a camera. But photographing a dark sky and having far-off cosmic objects be visible in the shot can be tricky.

If you spot Comet NEOWISE, let us know! Send images and comments to [email protected] to share your views.

Amateur astrophotographer Bill Dunford, a social media specialist at NASA's Jet Propulsion Laboratory (JPL), recently shared his experience photographing the comet in a video along with some helpful tips and tricks.

"In my spare time, I love to take pictures of the night sky," Dunford said. "I do this using a camera mounted to a tripod."

This part seems obvious, but Dunford adds that he puts the camera "in manual mode so that I can set the camera to leave the shutter open for several seconds to let in lots of light." A four-second exposure should do the trick, he added.

He shared some of the photos of Comet NEOWISE that he took using that four-second exposure and added that he made sure to go skywatching far away from bright city lights.

When Dunsford captured the image below, Comet NEOWISE was visible in the early-morning sky before sunrise. The comet has since left the predawn sky and is now visible in the evening just after sunset.

"On a clear morning at about 4:30 a.m. I went to a location far from city lights," Dunford said. "I could see the comet with the naked eye so I zoomed in on it and exposed each shot for about four seconds."

Dunford also shared that he "did a little post-processing using photo editing software." Using this software, he was able to brighten up his photos a bit, "draw out the vibrancy of the colors and clean up some noise. The end result was close to how the scene looked in person which, I have to tell you, was beautiful."

Lastly, he shared: "I really hope you get a chance to see the Comet NEOWISE and all the other wonders of the night sky."

Here's a NASA sky map showing where to look for Comet NEOWISE in the July's sky.

## Is bright Comet ATLAS disintegrating?

Images of Comet ATLAS – taken on April 5, 2020 – show an elongation of the comet’s nucleus. The elongation is aligned with the axis of the comet’s tail. Astronomers have seen before that comets exhibit this sort of elongation shortly before disintegrating. Image via astronomers Quanzhi Ye (University of Maryland) and Qicheng Zhang (Caltech)/ Ningbo Education Xinjiang Telescope.

Updated April 11, 2020.

Recent observations of Comet C/2019 Y4 (ATLAS) show that it’s fading in brightness. According to observers’ reports, after gradually brightening to magnitude 8 as it crossed Mars’ orbit, the comet has appeared fainter during the last few nights. It has sunk to a magnitude of around 8.8 to 9.2 (the bigger the number, the fainter the sky object). Is Comet ATLAS disintegrating? Are our hopes for a bright comet – or even one visible to the eye – dashed? It appears so.

Astronomers Quanzhi Ye (University of Maryland) and Qicheng Zhang (Caltech) submitted an astronomical telegram titled Possible Disintegration of Comet C/2019 Y4 (ATLAS). According to their telegram:

We report the possible disintegration of comet C/2019 Y4 (ATLAS), revealed by the public monitoring program carried out by the 0.6-m Ningbo Education Xinjiang Telescope (NEXT). Images taken on UT 2020 April 5.6-5.9 showed an elongated pseudo-nucleus measuring about 3 arcsec in length and aligned with the axis of the tail, a morphology consistent with a sudden decline or cessation of dust production, as would be expected from a major disruption of the [comet’s] nucleus.

In the days following the original announcement, other observers also began reporting signs of disintegration:

Does this mean the end of Comet C/2019 Y4 (ATLAS)? Probably. However, time and time again, comets have shown themselves to be erratic and unpredictable. In case Comet ATLAS does remain visible – and in one piece – EarthSky shares some charts below to help you find the celestial visitor.

View at EarthSky Community Photos. | Photographer Steve Pauken in Bisbee, Arizona, said: “Comet C/2019-Y4 Atlas on April 2. Getting a bit brighter.”

Original article is below. Be aware that, if the comet has faded – as now appears likely – all bets are off for brightness predictions.

A recently discovered comet is getting the attention of astronomers and sky enthusiasts as it’s become brighter than expected in the last few days. Astronomers using the ATLAS (Asteroid Terrestrial-impact Last Alert System) in Hawaii discovered Comet C/2019 Y4 (ATLAS) on December 28, 2019. As of mid-late March, it shines at about the brightness of an 8th-magnitude star – not visible to the eye yet – but within reach of medium-sized telescopes in dark skies. The comet is currently crossing Mars’ orbit and is approaching the inner solar system. As it gets closer to us, it’ll get brighter still. You’ll find charts for observers at the bottom of this post.

Comet ATLAS should become bright enough to be easily visible in binoculars, and perhaps bright enough to be seen with the unaided eye from dark sky locations.

Just know that comets are notoriously erratic and inherently unpredictable! We will have to wait to see how Comet ATLAS performs.

View at EarthSky Community Photos. | John Grage captured Comet ATLAS from Mind`s Eye Observatory in Sebastian, Florida, on March 28. He said: “This image was taken while performing first light with a new camera and doing my part for social distancing … something most amateur astronomers happily do nightly!” Thank you, John! View at EarthSky Community Photos. | Abhijit Patil captured Comet ATLAS on March 27, 2020, from near Killington, Vermont. He wrote: “The first comet I have ever seen or captured with a camera or naked eye. It was thrilling to see it and take a photo of it in my camera. All things learnt in school are coming to life with this hobby. Comet Atlas Y4 was discovered in Dec 2019. It is at a distance of approx 72 million miles from Earth at its closest approach. The nucleus of the comet is 10 km in diameter while the gases around it spread a few miles across. The comet is visible in the night sky in the North direction and can be seen through small telescopes. It is expected to brighten in the coming weeks. It should be visible to the unaided eye from dark sky sites.” Steve Pauken in Bisbee, Arizona, caught this image of Comet C/2019 Y4 (ATLAS) on March 16. He wrote that the comet is: “… supposed to get brighter slowly until mid-May. Since no one else wants to sit in the cold evening air with me, it’s a great way to practice social distancing. :-)” Another great image of Comet C/2019 Y4 (ATLAS), by Efrain Morales from Aguadilla, Puerto Rico. The marked object is a distant galaxy.

Astronomer Alessandro Marchini, director of the Astronomical Observatory at the University of Siena in Italy, sent the video below on March 21, the day after the death toll from COVID-19 in Italy had ramped up dramatically. He wrote:

During this surreal period of the health emergency for the Covid-19, I’m trying to use our social channels to entertain people forced at home. This evening I observed the comet C/2019 Y4 ATLAS during a Facebook Live streaming and here is a time-lapse I made with the images I acquired with our telescope. I hope all is fine with you.

Thank you, Alessandro, and please stay safe.

Comet C/2019 Y4 (ATLAS) will come closest to Earth on May 23, 2020. Its perihelion or closest approach to the sun will occur on May 31, 2020.

If predictions are correct, Comet ATLAS might reach a visual magnitude of +5 around May 1, 2020. That is theoretically bright enough to be see with the unaided eye, but the fuzziness of faint comets can make them harder to spot than comparably bright stars. When looking for fuzzy objects, it’s best to use averted vision: explanation here.

How bright will the comet get after that? Estimates of Comet ATLAS’s peak brightness range from magnitude +2 to -6 during perihelion or closest approach to the sun, but please know that many comets fizzle and never reach their expected brightnesses. We will have to wait and see.

Orbit of Comet C/2019 Y4 (ATLAS). Image via NASA/ JPL.

How close to our planet will the comet come? The celestial visitor will pass at a huge distance, at some 72,610,769 million miles away (116,855,706 km).

Comet C/2019 Y4 (ATLAS) will pass very close to the sun, and thus may disintegrate before becoming bright enough to be seen with the unaided eye.

It will pass at some 23,517,819 miles (37,848,261 km) from the sun, which is closer to our star than Mercury’s elliptical orbit (about 36 million miles or 57.9 million km on average).

Calculations by NASA/JPL indicate Comet ATLAS takes some 6,025 years to complete an orbit around the sun. Observations show it has a similar orbit to the Great Comet of 1844, which suggests that Comet ATLAS may be a fragment of the same 1844 comet.

Will Comet C/2019 Y4 (ATLAS) provide a good show or just fizzle out? Let’s keep a close eye on it, just in case! Bookmark this article, as we’ll provide updates and new photos when we can …

Here are some charts for you.

Location of Comet C/2019 Y4 (ATLAS) in late March 2020. This chart faces north-northeast from a temperate latitude in the Northern Hemisphere. The time is around 9 p.m. local daylight (8 p.m. if you’re not using daylight time) for all locations. In late March, the comet requires a small or medium-sized telescope, but it may be visible in binoculars very soon! Illustration by Eddie Irizarry using Stellarium. Location of Comet C/2019 Y4 (ATLAS) during late March 2020. Facing north-northeast at around 9 p.m. local daylight time (8 p.m. if you’re not using daylight time) for all locations. In late March, the comet requires a small or medium-sized telescope, but it may be visible in binoculars very soon! Illustration by Eddie Irizarry using Stellarium. Location of Comet C/2019 Y4 (ATLAS) during early April 2020. Facing north at around 9 p.m. local daylight time (around 8 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium. Location of Comet C/2019 Y4 (ATLAS) on April 15, 2020, around 9 p.m. local daylight time (around 8 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium. Location of Comet C/2019 Y4 (ATLAS) on April 30, 2020, around 9:30 p.m. local daylight time (around 8:30 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium. By May 15, 2020, Comet C/2019 Y4 (ATLAS) will become increasingly closer to the northwest horizon. By then it might be bright enough to be easily seen with small binoculars, or perhaps even with the unaided eye! Illustration by Eddie Irizarry using Stellarium.

Bottom line: Recently discovered Comet C/2019 Y4 (ATLAS) appeared bright. Many hoped it would become bright enough to see with the eye alone. But in early April the comet began to fizzle.