It has begun. Mars is making the turn from its usual eastward progress across the sky. It will appear to move westward for the next two months. At the end of August it will slowly turn and head eastward again. Why? How can that be?
The answer is simple. Earth orbits closer to the Sun than Mars. We move faster than Mars. We are passing Mars at this time. It is the same perspective as when passing another car. The passed car appears to move backward relative to your faster car.
In addition, Mars grows in size when viewed through telescopes until the end of July. After that, it will decrease in size. If you have access to a telescope, look for Mars in the east after sunset. You’ll need a high power to see any detail. Let’s hope the dust storm settles to reveal those details.
The graphic below from BinTel illustrates the apparent change in diameter given in arc-seconds (“). At the end of July, the Moon will appear about 24″ wide. For reference, the angular diameter of the Sun, or a full moon, is about 1800”, half a degree. That is the width of your little fingernail seen at arm’s length.
Two contrasting headlines about recent climate in the U.S. this spring caught my attention. Both came from NOAA’s National Centers for Environmental Information. The headlines were from the assessments of climate in the U.S. for April and May of 2018.
• The contiguous United States had its coldest April in more than 20 years.
• The contiguous United States had its warmest May on record.
The part of the U.S. where you live might not have seemed unusual. However, we noticed these differences in the midwest. Before examining April and May specifically, we will look at the climate for the year-to-date in the next two graphics. Relative to the period from 1895-2018, the upper plains was below average in temperature for the first five months of the year. The west was above to much above normal with record setting temperatures in the southwest.
Not shown in the graphic, the Alaska year-to-date temperature was 20.7°F, or 4.9°F above average. It was the ninth warmest on record. Western and northern Alaska were much above normal. Record low amounts of sea ice in the Arctic likely contributed to the warming.
While a classroom teacher, I drew a lot of stick people on the chalkboard to illustrate physics topics. I enjoyed posing those skinny characters. The students got a kick out of them.
Lately, I was curious about drawing more realistic things. What techniques would help me do that? Melanie suggested I sign up for a drawing class from Craftsy to find out. So I did.
Booster Rockets are big, heavy, and expensive components essential to launching vehicles into space. The 12 ft diameter nozzles of the Saturn V booster from the Apollo era developed thrust of 7.5 million pounds capable of lifting the 6 million pound fueled rocket into orbit. Those boosters were not reused after they did their work and fell into the Atlantic Ocean. Cost saving is important, as are safety and reliability. Private companies are involved in the development of reusable booster rockets.
The previous visit by Comet Halley to our part of the inner solar system was in 1986. The time before that was in 1910. The next visit will be in 2061. I have not ruled out seeing it again.
The European Space Agency’s Giotto spacecraft flew within 600 mi (965 km) of Halley and through the tail in March 1986. The dimensions of the comet nucleus were seen as 15×8 km (9×5 mi) and shaped like a potato. Giotto confirmed the existence of organic matter and revealed the surface to be one of the blackest objects in space. Image enhancement was used to brighten the surface to reveal more detail in these fly-by images. Images are from ESA and affiliates.
Our friends had a fire.
Seventeen years ago, friends of ours moved from their in-town home to a 5 acre property several miles out of town. They built a beautiful prairie-style house and converted 4 acres of their alfalfa field front yard into a mixed prairie like it was 200 years ago. Native grasses, wildflowers, and trees were planted and a small pond was formed. The plantings grew well in the rich Iowa soil. Wildlife returned. Bird species grew in number. Kestrels nested in the box above the open space. Waterfowl visited the pond. They kept paths mowed to allow easy access to parts of the prairie visible in this satellite view.
Only one thing was missing from their prairie. They needed a fire. Much dry vegetation was on the ground built up from years of growth. Certain desirable native species were crowded out…
View original post 537 more words