Two nights ago the Starlink 6 train of satellites launched by SpaceX passed directly over our location at magnitude 0.8. Clouds were a problem. We were able to see about 10 of them briefly in a small gap between the clouds. Last night they passed again, but farther to the south and only 36˚ up from the horizon. The sky conditions were better but worsening. They were to be at magnitude 3.2 which is not very bright in our urban setting.
NightCap on the iPad does a good job capturing night time events. I set it for ISS passes and hoped for the best. We stood in a relatively dark place down the street while the iPad recorded a 6 min time exposure. We watched in amazement as the entire train of 60 Starlink satellites passed right-to-left across the part of the sky still clear. They were quite dim but we easily saw them pass. The clouds were steadily encroaching from the right.
The photographic results were a disappointment. The satellites passed under the Moon and barely under Canis Minor in the center before they became visible to us. Their trails are hidden behind the narrow cloud streak the goes from below Canis Minor and off the left side of the frame. Perfect placement for not being visible in the photo. I tried everything in Photoshop to adjust the image and make them visible. Nothing worked. But, we did escape from house confinement for a while and enjoyed the warm spring evening.
Taken with NightCap | ISS mode | 356 sec exposure
A total solar eclipse took place on 2 July 2019. It was visible in the South Pacific and the southern tip of South America. The eclipse was imaged by the NOAA GOES-West weather satellite stationed over the equator above the Pacific Ocean. The video plays the eclipse 3x.
Dark areas on the globe are nighttime. The shadow of the Moon appears at the sunrise night-to-day boundary in the South Pacific. It moves east toward the southern tip of South America. It disappears at the sunset day-to-night boundary.
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Synchronous Earth Orbits
This graphic from Boeing illustrates about 300 communication satellites were in geosynchronous orbit in 2012. They include Echostar and DirectTV, as well as those for Canada, Central and South America, Europe, Asia, Africa, and Australia. The ones colored blue are Boeing satellites. This graphic does not include the GOES weather satellites. They are parked in the same orbit as these shown. Click to enlarge for much more detail.
The detailed view shows the satellites spaced apart by small angular amounts directly above the equator. Over densely populated regions, where there are more satellites in orbit, they are 0.5˚ apart in the sky, the same as the width of a full moon. In less populated regions, as over the Pacific, satellites are 1˚, 2˚, up to 3˚ apart. All satellites are to remain in their assigned location and not drift east or west into the zone occupied by a neighboring satellite. Low-power rocket thrusters work periodically to keep them on-station.
Click enlarges for detail in a new tab.
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The concepts are simple to place a satellite or a manned space capsule into orbit near the Earth. But, they are very difficult to achieve.
- Engines must exert a lot more upward force than the downward force of the weight of the fueled rocket.
- After lift-off, gradually point the rocket more horizontally as it moves faster.
- Jettison the empty 1st stage. The 2nd stage engine(s) continues to speed up the payload horizontally.
- Shut down the engine(s) to allow the payload to coast in circular orbit when at altitude of about 120 miles (~200 km) and speed of about 17,500 mph (~ 28,200 kph).
The orbit drawn here to scale in yellow allows the spacecraft to coast for some time above most of the atmosphere. But it will not coast forever. The thin atmosphere will gradually bring it down.
Earth image from NASA
The U.S. started launching rockets from Cape Canaveral Florida in 1950. The European Space Agency launches from Guiana Space Centre northwest of Kourou in French Guiana. France established that space port in 1964. Each site has open water to the east avoiding the danger to populated areas. Each site uses the speed boost from the eastward rotation of the Earth to assist launch speeds. Guiana is near the equator and moves east about 1000 mph. Cape Canaveral moves east over 900 mph. With the better technologies today, rockets can be launched to orbit from about anywhere and in non-east directions such as for polar orbits.
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The Iridium 21 satellite passed over my part of Iowa this morning before sunrise. I set the iPad Air 2 on a firm base pointed at an angle toward the NNW sky. At 6:02 am, I started the 102 sec exposure using the NightCap Camera app, same as for the ISS pass three days earlier. The satellite was going north as it entered the frame at the top. After about 30 sec, a highly reflective mirror-like antenna cast a beam of sunlight down toward me. It brightened to several times more than the planets Venus or Jupiter ever get. Then it dimmed and continued north.
Taken with NightCap Camera | ISS mode | 102 sec | click to embiggen
Another satellite passed at the same time going toward the upper left from north-to-south. It is very faintly visible to the left of the flare. According to the Heavens Above database for my area, it was either a Russian satellite, or an Ariane rocket body.