December Showers

In the October 2021 issue of WGN, the journal of the IMO, it was suggested meteor observers submit observations from meteor showers with moon light present. Moonlight, something must of us meteor observers try to avoid, significantly affects how many meteors you can see. The aim of the project is to:

  • obtaining complete activity profiles of shower (maxima)
  • deriving reliable peak data for events occurring under poor conditions
  • improving value of daytime shower data (twilight observations)
  • determining the effect of sky background illumination quantitatively

This years Geminids offered a good chance to do that as will the 2022 Perseids. I reported on two showers:

Geminids (GEM)

Wasn’t planning on going out but the weather was ok and the chance for an hour in real dark skies was too alluring. So I went to the Flint Hills to observer the Geminids on 12/13. The hour from midnight to 1am had the sky full of moisture, thin bands illuminated by the moon. Moon was about 79% illuminated and I recorded 34 GEM even with that, bit surprising. As the moon got lower in the sky more and more meteors were visible. Total GEMs counted during nearly 4 hours observing was 190, a bit surprising. Temperature was so mild I could observer for long periods. The last hour or so the sky was nice and dark, well worth the trip. Clearly the Geminids are so strong they power through moonlight.

Ursids (URS)

The Ursids are not a very active shower but it certainly would be heavily affected by the strong moonlight. I did not travel for this opting to observer from my local area. The nearly full moon was out so why bother going anywhere! I got up early and observed starting about 03:45 on the 23rd. Cold morning but crystal clear. The moon was very strong being nearly overhead and 85% illuminated. I’ve never observed in such a moon light sky. Saw very few meteors, just two URS, with the sky around magnitude 4 naked eye limit.

Dark Sky Pilgrimage

Friday October 1st I drove across Kansas to the 38th Annual Okie-Tex Star Party. It has been two years since I made this trip, one I usually do every year. But 2020 wasn’t a normal year with everything everywhere being disrupted. I had gotten out to some dark skies in 2020, notably comet NeoWise. But this trip was different; out to a place more remote than most. Where the night sky is ablaze with countless stars, a place where there are no visible light domes in any direction, a place where those of us that treasure the night sky go.

Every Okie-Tex star party is different. Despite being held in the same location for 22 years each event has its own weather pattern, different blend of people that attend and unique night sky conditions. When the star party is scheduled depends on the moon, when it will be closest to new. This year that meant the start of October and for the first time the official starting day was a Friday.

My drive out that Friday was cloudy, something I like as it keeps the sun off me. It took a little under eight hours to travel out this year, just one refueling stop. Coming over the last hill to see camp Billy Joe full of people was a pleasing sight. Yet for the first time in many years I was arriving after most had already setup. For the longest time I had setup in the same spot on the field, as many other regulars do as well. But this year I moved a bit and setup differently. Not far from my old spot being close to several groups I know. This year would be a bit different though: new spot, new neighbor, and new things to try. Starting with power.

Continue reading “Dark Sky Pilgrimage”

Rained on my Perseid Shower

Sadly my timing was off this year as I was planning on a Thursday night trip out to dark skies for the Perseids. This timing would have put my observing after the usual 140 degree λ⊙ peak but still should have been decent activity. Thursday evening I had things packed and ready to roll but things didn’t work out as planned. Mother nature decided to throw a massive storm event over the area.

The infrared satelite image for 2:00am CST Friday morning

Yep, completely clouded over all around me 🙁

At least the cloud out for the meteor shower was not a total loss. My area really needed rain and by Friday morning 3.8 inches had fallen at my place.

Summer Solstice

Tonight is the summer solstice and as I write a cool front is pushing through. The clouds from the passing front have darkened the nearing full moon. It has been hot this past week, mid summer heat. To early. It has also been dry this month of June. The exact opposite of May when I recorded almost 9 inches of rain in one week. My yard went from a swamp then to bone dry now.

Most surprising has been the fireflies over the past weeks. So far tonight the fireflies have been out in good numbers. This is perhaps the best night of lightning bugs in my yard I’ve seen so far this year. Very nice show. I would not have guessed it would be like this a month ago.

Two years ago I had a very wet May much like this year. It was my observation then that the swampy ground was not something the fireflies liked. They were non existent and never put on much of a show. The same situation seemed to be unfolding this year as well. After the wet May I saw few if any fireflies. But over the last week the nightly numbers have rapidly climbed. Perhaps they favor this hot and dry weather my area has been stuck in. I am not sure what exactly influences their behavior but its fun to watch them. A yard full of fireflies is a simple pleasure. A treat you get to experience for a short while before they slowly disappear until the next year.

It Starts At Zero

Today at 09:37 UTC is the vernal equinox, the official start of spring in the Northern hemisphere where I am located. On this day the length of daylight and darkness at night is nearly the same and because it is not exact articles will be written and people will argue about it. Lost in all this is the fact that the equinoxes do not happen at exactly the same time every year. Look this up, last year the spring equinox was at 03:50 UTC on March 20th, almost six hours earlier than this year. Next year the spring equinox is at 15:33 UTC on March 20th, almost six hours later than this year. This highlights a problem with our calendar system: its messy to use for noting a position in space, where Earth is in its orbit around the Sun.

Simple geometry can give us an answer. Since the Earth’s orbit is nearly circular we can use the fact that there are 360 degrees in a circle to note where Earth is. This position is called solar longitude (Ls), denoted λ⊙, and is expressed in degrees. Knowing where Earth is in its orbit around the Sun is particularly useful in meteor science. At certain points in our orbit Earth crosses a stream of particles that produce what we call a meteor shower. So how do we create a reference for that not based on a calendar? We start by using the equinox.

The equinox is defined as the moment the plane of Earth’s equator passes through the geometric center of the Sun’s disk. This moment of equal day and night, or a precise point where the sun rises or sets on the horizon has been used for a long time in human history. As the Earth orbits the Sun it crosses this point because Earth’s rotation is tilted. In the spring equinox the Sun moves above the Earth’s equatorial plane and in fall it moves below that plane. These moments can be used as a precise reference if another point is used, a star(1).

Today at 16:32 UTC solar longitude is zero degrees.

Choosing the spring equinox as the start, or zero degrees, is an arbitrary choice. I do not know why the choice was made, historical significance? Perhaps a reference star is better in spring then fall? Research for another day. But the point chosen is an exact spot, a reference we can use to start marking the circle that represents our orbit.

When a meteor shower happens is noted by solar longitude to mark the position when Earth moves through the center of the orbit of particulate debris causing the shower. In other words, typically when the maximum of a meteor shower occurs. For example, the peak of the Perseid meteor shower happens at 140 degrees λ⊙. This translates to August 12th at 19:17 UTC for this year, in 2022 it will be August 13th at 01:32 UTC.

The reason why the equinox does not happen on the same date time every year is our Julian calendar system has 365 days in a year (366 during a leap year). In a year the Earth completes one revolution around the sun, or 360 degrees in a circle. This is the problem: 365 days in a year verses 360 degrees in a circle, our way of tracking dates and time gets out of sync with the exact location we are in space.

  1. We have to go a step further to be precise in choosing this point because everything in the universe is in motion. So we use a specific epoch ( )

Geminids 2020

Outlook for the 2020 Geminids was pretty good, essentially no moon and with the normal peak (λʘ= 262.2) occurring about the time the radiant was rising above the horizon for my timezone (CST). This meant I would be observing after the peak but close enough. Last question was weather: would it be clear?

Sunday December 13th it was clear and should stay that way, off to the Flint Hills for some meteors! I got to Teterville after dark and found the NW wind pretty steady at 10+ mph which was very annoying when temperatures are 24℉. Everything setup I started observing a bit after 20:00 CST.

Meteors were not very numerous at first but not unexpected as the radiant was only about 30° above the horizon. By midnight rates were much better, over 1 Geminid per minute. I had to take warm up beaks every so often as temperatures were about 20º F with 5 – 10 mph wind. Bit chilly. Frost was a serious problem for my cameras and they were knocked out after the first hour unfortunately.

The 2020 Geminid meteor shower turned out great, very nice display with many bright fireball level meteors. The night sky had been clear and magnificent with the winter constellations prominent all night. My total effective time observing was 4 hours and I logged 211 Geminid meteors. The choice of observing location south of Emporia was very fortunate, driving home I ran into thick ground fog north of my location. The sky was completely overcast from Emporia all the way north to Lawrence.