 Welcome to the Skides over Colorado for April 2021. I am staff astronomer John Ensworth of the Cherrywood Observatory, volunteer at the Little Thompson Observatory for Longmont Public Media. Astronomy news this month. We are back to looking at the Perseverance rover on Mars and a helicopter. Perseverance has a helicopter on board. You can see it here pictured mounted below the rover, the rover's landing platform, and the arm grabbed it early this April and moved it off to the side. Remember that this launched July 2020, landed last month 2021. This is an artist's rendition of what it will look like and the first flight is expected somewhere around 11th of April. The helicopter itself is called Ingenuity, here's a picture taken by the rover itself of the helicopter about 11 feet away, clear of everything and ready for its first test flight. There's a close up of the little thing, this is pretty amazing that they've come up with blades and motor speeds, power sufficient to operate in the very thin Martian atmosphere. We haven't had many comments just recently, and Common Atlas is our best for April that we know of. It's not going to be great, but here's a picture from the end of March. It's not large, it's got a good greenish color, it's going to move very rapidly this month. From the constellation of Aquila up to Canis venicenti, it's pretty dim, it starts out magnitude 12 so many large telescopes could see it, but then it gets up to around the 8th magnitude when it passes closest to Earth a little bit later this month. So that would be good in a 6 inch telescope or so, and you can usually find someone who has a 6 inch scope, give you a bigger picture. So this is about 3 o'clock in the morning, here is Atlas beginning near Aquila and it heads up to Canis venicenti. We have good news to report that we will not be destroyed from an asteroid coming in from space, at least not this one, Apophis. We have known of Apophis for a while and we had a conceptual spot in space just above the Earth called the keyhole that in a future flyby if this asteroid, which is about 1100 feet long to 20 million tons, happened to go through that keyhole then it would definitely hit the Earth in 2068 causing fantastic amounts of destruction even far from where it hit. 99942 Apophis with very very careful measurements here is March 8th, 1910, has now been proven to probably be a little further than we thought originally, about 950 feet further from this 600 meter wide spot, this keyhole than we thought. So that's true, it's not going to hit Earth at all, extremely vastly ridiculously small. Who cares? Chance. Alright, let's take a look at big star parties. Yeah, the news hasn't changed much, couldn't find anything in April, which would normally be pretty active time. In May the Texas Star Party had a date of May 2nd through 9th in Fort Davis type of air. Yeah, that's been canceled. So if you want to keep an eye on these things, I've got the two rather large URLs here on the screen and you can keep looking to see if something does get scheduled and stay on the books. Your astronomy 101 lesson for this month is related to something we spoke of before where we talked about the shadow of the Earth at sunset and sunrise visible in the atmosphere in the belt of Venus. Now we're going to talk about types of twilight, both evening and morning. These are very mathematically defined. Civil twilight occurs in the period of time that the Sun is just below the horizon to 6 degrees below the horizon. Civil twilight, civil dawn, civil sunset, down to 12 degrees below the horizon is nautical twilight and 18 degrees down is astronomical twilight and beyond that you're in full night. So you usually want to see the end of astronomical twilight to really get out there and start looking for dim fuzzies in the sky. So civil twilight, the end of civil twilight, street lights are usually programmed to come on, car lights should be on. This is that time where contrast is kind of difficult, I don't know if more car accidents happen then, but people feel less safe at least when they're driving. A nautical twilight looks like this. The brighter navigational stars are now visible, so if sailors in the past using the sextant and other navigational aids would be able to look at the position of the bright stars. At the time when they had good timepieces, and that's a really interesting story to look up historically to figure out where they were. That's the earliest and the latest you could navigate by astronomical night time objects. Astronomical twilight, you're starting to see lots of stars come out. You might still have a little bit of light in the western sky but the sky is now becoming fully dark. So a quick contrast, you can see the street lights are now fully on in nautical. And now you're having to take a time lapse to see details on buildings making building illumination very bright. The sky is above your backyard this month. We have the last quarter moon on April 4th in the morning sky. New moon happens on the 11th first quarter so the moon's back in the evening sky after about the 12th or 13th or so you can see that little sliver in the southwest and by the 20th it's first quarter with the full moon at the end of the month on the 26th. The planets, well we have one in the evening sky. In the dusk in the evening it's just Mars high up in the southwestern sky and it sets a couple hours or an hour before midnight. So in the evening this month you do have dim Uranus out there but you're not going to find it easily. It's so close to the sun it's so dim it's basically gone in the glow now. In Venus if you happen to catch it maybe with the telescope going right over the look we'll start to emerge from the sun's glow to make an appearance in the evening sky for much of the rest of this year. Taking a look at the big picture here this is right after sunset you can see the glow of the sun over this little graphical hill there's Uranus down here in the glow and Mars is pretty high up still. On the other side of midnight it's not much. Mars is going down at about 11.30, 11.45 in the middle of the month so yeah in the middle of the night midnight you are planet free. In the morning sky Neptune and Mercury are too close to the sun to be seen but Jupiter and Saturn are now putting on a nice show. So here's the morning sky with a little bit of glow from the rising sun and Neptune too close really for anything to matter. Here's Jupiter and Saturn because of the angle the ecliptic at this time of year they are really low in the southeastern sky even though they're getting kind of far from the sun. Sunrise the sun for April, April 1st sunrise is at 6.43am and we gain 45 minutes of light on that side of the day by April 30th. Sunset is at 7.24 and we end up at the 7.53pm sunset at the end of the month and so our sunlight now increases by about the same about half hour. So overall we go from 12 hours 40 minutes to 13 hours and 51 minutes giving us an hour and 10 minutes more daylight. The noon time local noon sun angle up from the southern horizon increases 10 degrees from 55 to 65 degrees. It still has a way to go for our June summer solstice. Our feature object this month is one of the only planet that you can see with the naked eye and with small telescopes that we haven't covered yet and that is Venus and since Venus is coming into a good show for the rest of the year might as well bring it up now. This is a false cover, false color, sorry image lots of enhancements done on that that's probably a spacecraft based image and yet but right this is what you most normally see down the lower right with Venus being the brightest thing that is a point like object in the night time sky. It is brighter than Jupiter that Jupiter is given a higher billing because it is a superior planet we talked about that in an earlier video it goes all the way around the night time sky throughout the year or Venus can get up to 46 or so degrees away from the sun at best. It is a weird planet though it is almost exactly the same size as the Earth 95% of our diameter with about 90% of our gravity at its surface. Its year is 224 to 225 Earth days long but its day is 243 Earth days long so it actually rotates backwards so its day is longer than its year. That gives it or results from what we call a 177 degree tilt in its axis it is upside down. We define North by looking down from above a counterclockwise rotation so North is wherever that happens as you're looking at the rotating whatever it is. The Mercury last month which has almost no atmosphere this has a crushing atmosphere with pressures down at the surface similar to being a mile down in the ocean. All carbon dioxide so does suffocating temperatures in the many hundreds of degrees 800 degrees or so should have written that one down hot enough to melt lead and the clogs above rain sulfuric acid droplets down until they evaporate so it is a pretty nasty place. Your Colorado Observing Challenge this month is to look to see if the moon really is bigger as it rises and sets than it is in the high portion of the sky. This is an optical illusion where your brain is trying to use nearby reference points like hillsides and trees and buildings to estimate the size of something just beyond them because your eyes can't see the parallax or the distance effect caused by the separation between your eyes for an object that is 200,000 miles away. So it says wow that's really big and then high in the sky it's this white circle surrounded by a whole bunch of nothingness and your brain says wow that's really small. So you can trick yourself by turning your back and looking under your arm or between your legs if you're flexible enough to see if the moon seems to pop back to normal size. You can look at the moon and then get out a paper towel roll and look through it and that takes away all those references and the moon should look normal size again or you could take a digital camera image and take a picture of it at rise and in the middle of the night. So astronomers without borders has challenges like this and I grabbed this one from them this month. Alright astronomy events near Longmont not unlike the star parties most things are shut down but there are still opportunities out there. The Longmont Astronomical Society on April 15th at 7pm will have a zoom meeting how do galaxies get their shapes with Dr. Angela Collier you can see longmontastro.org for details. They don't have any outdoor open space star parties planned that I see on their site. If I'm following their pattern correctly it should have happened or should have happened around April 16th at 6 30 or 7 30 p.m. kind of hard to tell I don't have an archive of their site so keep an eye on their site eventually things are going to go back to normal. Little Thompson Observatory they are closed through June 2021 and then July is a maintenance month so what for things in August you can schedule a virtual meetings which is done via zoom and you can look through the telescope basically from your home very limited it takes a lot of work and we only have a few volunteers who can be there at a time but keep an eye on that site for those and zoom meeting. Estes Park Memorial Observatory is still mostly closed they are going to try to start doing limited single group only meetings groups under 12 no more than three times a week I'll go ahead and read the text here on the details so currently the plan is to start hosting small star gazing groups in mid-April groups will be limited to just one family group or group of friends at a time it's be good but not required that everyone is vaccinated it could group screaming of a family's close friends classmates but I don't mix with unvaccinated outsiders everyone needs to wear a mask during the event only six will be allowed in the dome of the time to allow social distancing and since there is only the director Mike Conway they do want to limit it to three times a week so you have to go to angelsabove.org and send an email to the info address or look to call the phone number also on that site. Northern Colorado Astronomical Society has a webinar speaker April 1st Dr. Fran. Juno's extended mission in Jupiter the webcast so look for the archive there since this is going to go up a little after the first this planetarium they have down-to-home virtual programs live event April 15th at 7 p.m. a crowded orbit the co-evolution of satellites and space junk so visit colorado.edu slash this and the observatory there they ask you well there's one part that says to look for a meeting every Wednesday at 3 p.m. for live shows I do see specifically on the April 2nd at 8 p.m. April 30th 8 p.m. scheduled at their YouTube channel so explore there yourself see what you can find all right wrapping up this month take a look at our desktop software suggestion and I've given you some pretty high dollar ones so I'm going to go the other extreme now this is called Stellarium I also have this installed on my phone and iPad it's a free open-source planetarium and it is constantly being developed and improved it's pretty fantastic here's an example of the star map lots of controls very pretty sky it generates you can pick locations anywhere in the world and also pick different scenes for your horizon and feel that you're standing in probably even import your own you can generate orbits and highlight planets put things in motion in real time bring up constellations and lore you can even import different constellation sets from different cultures and you can overlay more fanciful imagery for those constellations go to Stellarium.org it is free you can download Linux Mac OS windows and even access it on the web pretty powerful software if you have any additions or corrections from this month or suggestions for future shows please email me jenonsworth at gmail.com and you put skies over colorado in the subject line so I know that this is what you're talking about this has been steep staff astronomer almost got to be without a good mess up staff astronomer jononsworth for long month public media see you next month keep looking up