Seeing comet NEOWISE?

Question

Today the NY Times published an article that explained how to see NEOWISE at night.

The article explains it like this:

To catch NEOWISE yourself, look up at the northwest skies about an hour and a half after sunset. Experts suggest going to the darkest area you can for best viewing. Find the Big Dipper and follow its ladle as it arcs in the direction of the horizon.

NEOWISE will appear under the Big Dipper about 10 degrees above the horizon and be about as bright as that constellation’s stars. If you hold out your arm, 10 degrees is roughly the part of the sky covered by your fist. Over the next few days, NEOWISE will move higher in the sky and be easier to spot, reaching its apex on July 23, when it makes its closest approach to Earth.

It says that I'll be able to see the comet "under the Big Dipper about 10 degrees above the horizon".

What "horizon" is the article referring to? It says above the horizon and under the Big Dipper. Is the Big Dipper just above where the sun disappears and the comet will be seen in that area?

Answer 1

Horizon

The horizon is Earth's horizon ... absent any obstructions such as buildings, trees, etc. Or another way to think of it is the horizon you would observe looking out across the ocean while standing on a beach.

The notion that it is "10° above the horizon" means that from the horizon line, it would be 10° up. You closed fist (as if you are about to punch someone) measure about 10° (from your thumb to your pinky finger) if held at arm's-length. Close your fist and extend your arm ... placing the bottom (the edge along the side with your pinky finger) on the horizon. 10° up is roughly where the knuckle of your thumb is located.

Caveats: Time and Date

But a couple of cautions should be mentioned regarding the article...

Objects in our Solar System move from night to night and this motion can sometimes be noticed even from hour to hour. Tonight (July 21, 2020) it is still below the "bowl" section of the Big Dipper asterism. But in a few days that will no longer be true. One week from today it will no longer appear "below" any part of the Big Dipper asterism. It is heading through the Coma Berenices constellation.

Also, the 10° measurement... this assumes both a time in the evening AND a latitude on Earth.

I'm located at roughly 42° North latitude. At 10:30pm for me and tonight (because time and date both matter) the comet is 22° above the horizon. But if I wait an hour and check 11:30pm ... comet is only 14° above the horizon. This is because the comet is setting ... sort of. Technically if you are far enough North the comet doesn't "set" below the horizon. Since I am located at roughly 42° North, anything with 42° of the celestial pole (near the North Star) doesn't actually "set" below the horizon. It will be up all day and all night. But as dawn approaches and the twilight brightens, the sky glow will wash out the comet until it is no longer possible to view from any "daytime" part of the planet.

Cheating

Rather than trying to imagine where the comet is, there's a much easier way to just nail it.

Technology has come a LONG way over the years. These days, you can get an app for your smartphone that will tie into the GPS, compass, and level/tilt/gyro sensors on your phone. It's amazing how well this stuff works. You hold the phone up to the sky, and it knows everything in the sky that should be visible from your current location and in that direction. It will literally draw the sky and show you the precise location of the comet.

Answer 2

The article just refers to the earth's horizon. Neowise can be seen about 10 degrees above where the sky meets the earth.

Answer 3

The comet will be roughly 10 degrees above the Earth's horizon. But the horizon is a pretty vague indication as to where to look. To know what direction on the horizon to look towards, find the big dipper. The comet will be between the horizon and the big dipper.

Answer 4

I've been watching the comet for the last few nights from 50+ deg North, around midnight. A simple way to find it is to imagine the comet has been poured out of the end of the Big Dipper and is falling headfirst toward the horizon. It wouldn't hurt to imagine a strong wind has blown from behind the Dipper's handle and over cup to push the comet a little ahead of the Dipper over the next few days.

I'm fortunate to live in an area with dark skies. Typically around SQM 21.44 on clear nights.

I first saw the comet on Thursday July 16. That night the sky was exceptional clear and dark. A naked eye look to the North was all that was necessary to find it.

The comet was roughly about as bright as the brighter parts of the Milky way that night. A bit of aurora would wipe it out. The comet was an impressive sight but in all honesty, not an award winner.

Someone with much younger eyes that has never seen a comet would likely be a bit more enthusiastic in their description.

It is well worth the trouble of trying. A good pair of binoculars should be on hand just in case. Seeing the last few nights has been a little below average but the comet was still easy to find.

With binoculars under a not too badly light polluted sky the comet should be visible about an hour after sunset.

Good Luck and don't pass up this chance. Comets this bright are few and far between. This one will not likely win any awards but you will remember it even after a few more have come and gone.

Answer 5

The verbal description in the NYT article is correct but not precise enough to locate the comet in practice. Here is a finder chart generated by Stellarium for 90 minutes after sunset at New York City and similar latitudes. The Big Dipper is at the top, just to the right of center. The cyan dots indicate the comet's position at 21:50 EDT from July 22 to 31. The horizon is at the bottom; sunset occurs about 60% of the way from the W marker to the NW marker.