Greetings stargazers.
Last week, a rather large meteor hit the atmosphere over eastern Massachusetts. It was seen during the daylight by many people and heard by many more. This event was not unusual. It is estimated that hundreds of such objects hit the United States every year. Most of them do not make the news because they don’t hit over populated areas.
These types of 3- to 5-foot diameter space rocks are some of the hardest objects to detect before they hit because they are too small to be seen in telescopes. Once they hit the atmosphere, most evidence of their existence is burned up, so getting accurate statistics is a challenge. If anything remains to hit the ground, it is most likely buried and no one was watching to see where.
During the Artemis II mission, one of the science activities was to count the visible meteor strikes on the moon while the spacecraft was in the moon’s shadow. In the brief time that the capsule flew by, the bright flashes from six separate impacts were spotted. The Earth is a bigger target and has a greater gravitational field to attract meteors, so it is expected that many more are hitting the Earth all the time.
Without accurately knowing the mass and velocity details, estimates of the energy deposited in the atmosphere are just that – estimates. For the Massachusetts meteor, the estimate I saw was that it was equivalent to 300 tons of TNT. That unique unit of energy is used exclusively for the yield from nuclear weapons. For comparison, the Hiroshima bomb was about 20,000 tons, and the Chelyabinsk meteor that his Russia in 2013 was around 500,000 tons.
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The conjunction of Venus and Jupiter is certainly the most obvious thing in the sky right now. Planetary conjunctions are not particularly rare. Since planets orbit the sun at different speeds, one is always passing another one from our perspective on Earth. This conjunction happens to be between the brightest planets we can see. They have been slowly approaching each other for a while and will still be near each other a while longer. Mercury is a bit harder to see, because it is dimmer and closer to the horizon. On Tuesday, the crescent moon joins the party and will be mid-way between Venus and Mercury.
The Big Dipper is at its highest point right after sunset. The pointer stars Dubhe and Merak are slightly west of due north and pointing down and to the right toward Polaris. The handle is pointing almost straight up. You can try to remember that the handle “arcs to Arcturus” as it points toward the bright star Arcturus, which is nearly overhead. If you are just learning the constellations, this is a great one to start with. However, the asterism of the Big Dipper is only one part of the much larger constellation Ursa Major. In addition to the seven stars that make up the dipper, the rest of the stars that represent the bear are much dimmer.
Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory. Reach him at hakes_c@fortlewis.edu.
