David Forester
LightNews LightNews
arborscientiae.bsky.social
David Forester
@arborscientiae.bsky.social
240 followers 180 following 480 posts
I teach astronomy, biology, and chemistry, and I coach esports. Hobbies include hiking, biking, climbing, drumming, gaming, and photography.
Posts Replies Media Videos
arborscientiae.bsky.social
What year is it‽
A man with a beard wearing brown with a cowl of green leaves and a large leaf hat. He is dressed as Alan Parrish from Jumanji. He has a surprised expression on his face. Behind him is a hedge of green leaves. A man with a beard wearing brown with a cowl of green leaves and a large leaf hat. He is dressed as Alan Parrish from Jumanji. He's in the middle of asking what year it is. Behind him you can see the tree canopy above.
October 31, 2025 at 4:04 PM
arborscientiae.bsky.social
Time to re-inoculate myself.
xkcd comic that reads, "You just won the game. It's okay! You're free!" This is handwritten in black on a white background.
October 25, 2025 at 5:43 PM
arborscientiae.bsky.social
Someone posted this on Reddit. Sort of an extreme example but still, even using the 15 for some of the shorter trips winds up more than quadrupling travel time. Even something like Carlsbad to Irvine would see its time more than doubled using the 15.
A map showing the estimated travel time from Oceanside to San Clemente as 2 hours and 17 minutes when it would normally be about 30 minutes. The map also shows that the five freeway along Camp Pendleton is shut down due to a Trump ordered military demonstration involving live fire from a naval ship across the freeway into the marine base.
October 19, 2025 at 6:23 PM
arborscientiae.bsky.social
I didn't make it to the big event downtown, but one of several local satellite protests still pulled at least a thousand people spread across a couple streets. #NoKings
A large crowd of people stretches down the street. They're holding anti-Trump protest signs and waving American flags. Cars are honking and waving as they drive past.
October 18, 2025 at 8:18 PM
arborscientiae.bsky.social
Leaving dinner with the family and... rocket launch!
Wide angle shot of noctilucent cloud left from a rocket trail passing in front of the moon and dark blue sky. It starts as a wispy line that curls into a sort of spiraling zigzag.
September 29, 2025 at 2:21 AM
arborscientiae.bsky.social
The cover art for the album "Waiting" by musical artist "Thursday". It is mostly black with a landscape orientation photo in black and white that shows a car sitting in the middle of a snowy scene with a bleak cloudy sky.
September 9, 2025 at 1:00 AM
arborscientiae.bsky.social
A green pair with a mouth full of too many teeth, and no eyes, is saying"LOL WUT". The pair is sitting on a grassy hill with white flowers, in the background there are giraffes and a lighthouse.
September 2, 2025 at 7:02 PM
arborscientiae.bsky.social
Sharing one of my favorites for #InverteFest: Cotinis mutabilis, the figeater beetle. The pictures are about 10 months old, but I figured I'd dust them off. This one was raised as a class pet from the larva I found in my backyard.
A close-up of a figeater beetle clinging to a piece of wood. Its exoskeleton is a shiny iridescent green with a golden brown trim around the border. A close-up of a fig eater beetle on a dead leaf. Its exoskeleton is a shiny iridescent green that is a bit yellower in this light. Around the edge of its wing covers is a golden border.
August 27, 2025 at 1:44 PM
arborscientiae.bsky.social
Challenge: Post your last photo taken in DC to show what a hell-hole it is.
A winter sunrise outside of Washington DC. Snow is on the ground and the trees are bare against the pale sky, with orange just above the horizon. The Washington monument is a golden spire in the light of a January sunset while the sky behind is a grayish blue. In the foreground you can see part of the freeway as the image was taken from a moving car.
August 12, 2025 at 3:02 AM
arborscientiae.bsky.social
Sabbath number is 6 at most, thanks to a series of local bands that leads to Finch, who played at Reading and Leeds in 2003, along with Metallica. Though, I may still have a shorter connection somehow.
Lineup poster for the 2003 Reading and Leeds Music Festival. The yellow poster has black text naming dozens of bands, including Metallica and Finch.
July 10, 2025 at 5:05 PM
arborscientiae.bsky.social
This past school year my kid and I rode our bikes to school at least twice a week. After dropping them off, I would continue a couple miles further to my school.
A child wearing a blue helmet and a Minecraft backpack is riding their bike past trees on their way to school. Another set of bicycle handlebars can be seen in the foreground.
July 6, 2025 at 5:10 PM
arborscientiae.bsky.social
I've been waiting for this day for a long time! Longer than my teaching career. Here is a picture I took in 2014:
The primary/tertiary mirror for the Vera C. Rubin telescope being polished in an underground facility under the football stadium at the University of Arizona in Tucson. Several signs say LSST since it was called the Large Synoptic Survey Telescope at the time. The mirror blank is about 8 meters across, and the inner, more concave portion is being polished.
June 23, 2025 at 10:56 PM
arborscientiae.bsky.social
And here is San Diego (and the national average) as well. #ShowYourStripes
A visualization of average annual temperatures using vertical lines that are various shades of blue, white, and red. This chart shows the temperature change for San Diego from 1850 until present day. The last four decades are mostly red while the first century is mostly blue. A visualization of average annual temperatures using vertical lines that are various shades of blue, white, and red. This chart shows the temperature change for the United States from 1895 until present day. The last three decades are mostly red while the first five decades are mostly blue. The final decade is dominated by deep crimson lines, showing that the problem is continuing to get worse.
June 21, 2025 at 10:06 PM
arborscientiae.bsky.social
#NoKings Carlsbad had thousands turn out, potentially over 10,000, I couldn't actually see the full extent as the crowds extended beyond my line of sight in several directions. #MundusSineCaesaribus
A man wearing a black mask and a black shirt that reads "MUNDUS SINE CAESARIBUS" which is Latin for "A world without Caesars". On his shoulders is a child wearing a black mask and a rainbow tie-dye shirt, and holding a U.S. flag. A protest sign with a spiky blue turtle shell from Mario Kart. The sign reads "Blue shell the 1%". A protest sign that reads "IT'S SO BAD EVEN THE INTROVERTS ARE HERE". A T-intersection with both sides of all streets packed with protesters, and even more in the park behind. Many are holding signs and U.S. flags. In the background you can see many palm trees as well as the ocean. In the foreground are several cars, some of which were honking.
June 14, 2025 at 7:10 PM
arborscientiae.bsky.social
It looks like they fixed it by now, at least on the Grok website. (I don't have Twitter anymore.)
Grok is giving results that contradict claims of white genocide, and highlight the hypocrisy of giving a asylum to South Africans, all while throwing Elon Musk under the bus repeatedly.
When asked about Trump helping South African immigrants while deporting immigrants from other countries, Grok mentions the apparent contradiction, the aggressive nature of Trump's policies, the probability that this is all just to send a message, and that it is likely tied to the fact that Elon Musk is from South Africa and is a Trump ally. Grok AI says "No, there is no credible evidence of a "white genocide" in South Africa." A better library that this claim is amplified by far right groups and people like Elon Musk, and stems from allegations that have been debunked by experts and data.
May 15, 2025 at 7:45 PM
arborscientiae.bsky.social
Off topic, but for me the post right below this was Chris Hadfield using the term "rollicking success".
Two Bluesky posts in a row, by different users, using "rollicking" as an adjective in unrelated contexts.
April 27, 2025 at 3:00 PM
arborscientiae.bsky.social
It happened again earlier this week, a single digit number of minutes before I walked by (it oxidized to brown by 3 minutes later when I brought an admin over to see before removing it). It was only half completed, but already you can tell what it was going to be.
Half of a swastika in green on wet concrete. Some damaged leaves are on the ground nearby, presumably they were used to make the drawing. The same half swastika 3 minutes later according to time stamps. It has now turned brown due to oxidation, indicating that it was still very fresh in the first image.
March 15, 2025 at 2:49 AM
arborscientiae.bsky.social
Crap, my space nerd is showing, you meant the one that would be relevant to Judy Garland. But when I read the name, I immediately pictured this image of the other Margaret Hamilton standing next to all the code she wrote for the Apollo guidance computer:
Black and white photo of a woman with long hair and glasses standing next to a pile of binders full of computer code printed out on paper that stands as tall as her.
March 13, 2025 at 2:21 AM
arborscientiae.bsky.social
A green dinosaur named Yoshi from the Mario Bros universe.
March 11, 2025 at 4:47 AM
arborscientiae.bsky.social
I'm in this picture, it was taken right after I took this picture. Hint: I'm wearing a blue jacket and the same hat as my profile picture.
A crowd of hundreds upon hundreds at a rally for science on the UCSD campus. Many are holding signs.
March 8, 2025 at 2:57 AM
arborscientiae.bsky.social
#StandUpForScience
A large crowd of hundreds upon hundreds at a pro-science rally at UCSD. Many are holding signs. A large crowd of hundreds upon hundreds at a pro-science rally at UCSD. Many are holding signs.
March 7, 2025 at 8:48 PM
arborscientiae.bsky.social
This Nuttall's woodpecker (𝐷𝑟𝑦𝑜𝑏𝑎𝑡𝑒𝑠 𝑛𝑢𝑡𝑡𝑎𝑙𝑙𝑖𝑖) likes to hang out in my backyard, especially on the Fremont cottonwood (𝑃𝑜𝑝𝑢𝑙𝑢𝑠 𝑓𝑟𝑒𝑚𝑜𝑛𝑡𝑖𝑖) tree.
A woodpecker is perched on the side of a cottonwood tree. The bird has a black back and wings with white horizontal stripes, and a white belly with black horizontal stripes and some speckling. It's head is black and white with some yellow feathers near the beak, and is kept with red feathers on the top and back of the head. The rough bark of the tree is a light brownish gray with lots of small branches and twigs all around the bird. The sky is overcast with a light gray, leaving the bird as the only source of vibrant color.
March 5, 2025 at 6:30 PM
arborscientiae.bsky.social
Quote post with a picture you took in a National Park.

Carlsbad Caverns. 2024.
A massive cavern filled with a variety of stalactites and stalagmites, most of which are far larger than a person. Some are illuminated while others are silhouetted.
February 27, 2025 at 7:30 AM
arborscientiae.bsky.social
The beacon! The beacon of El Capitan is lit! Hope is kindled.
An upside down American flag hanging in a window backlit by the setting sun.
February 24, 2025 at 1:55 AM
arborscientiae.bsky.social
What I did last week:
An email from Trogdor to HR@OPM.gov with a bullet point list of five things. Item one says, "I was a man." Item two says, "Maybe I was a dragon-man." Item three says, "Maybe I was just a dragon." Item four says, "I was still Trogdor!" Item five says, "I burninated the countryside." The email is signed by Trogdor the Burninator.
February 23, 2025 at 11:35 PM