It was Jupiter by the Moon this Morning
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My wife called me this morning – her students were asking “what planet was by the Moon this morning?” There was frost on the ground (and cars), the air was very crisp, and apparently there was a lot of earthshine on the Moon. Jupiter was 1.4° south of the Moon in this morning’s sky. Even though the Moon was just a thin waning crescent, the students said it was very bright. Good on my wife’s students for witnessing this conjunction! … Continue reading

Juno Close Approach to Jupiter This Saturday
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This Saturday at 5:51 a.m. PDT, (8:51 a.m. EDT, 12:51 UTC) NASA’s Juno spacecraft will get closer to the cloud tops of Jupiter than at any other time during its prime mission. At the moment of closest approach, Juno will be about 2,500 miles (4,200 kilometers) above Jupiter’s swirling clouds and traveling at 130,000 mph (208,000 kilometers per hour) with respect to the planet. There are 35 more close flybys of Jupiter scheduled during its prime mission (scheduled to end in February of 2018). The Aug. 27 flyby will be the first time Juno will have its entire suite of science instruments activated and looking at the giant planet as the spacecraft zooms past. “This is the first time we will be close to Jupiter since we entered orbit on July 4,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “Back then we turned all our instruments off to focus on the rocket … Continue reading

Jupiter Looms as Juno Approaches July 4th Arrival
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The Juno spacecraft has been in the gravitational embrace of the planet Jupiter for a month now, and is quickly approaching the moment it will ignite its thrusters, and enter into orbit over Jupiter’s poles. Juno may have some very interesting things to see, if aurorae spied by the Hubble Space Telescope in recent weeks continue to swirl around Jupiter’s north pole. Follow Juno on July 4 — Orbit Insertion Day: Noon EDT — Pre-orbit insertion briefing at JPL 10:30 p.m. EDT — Orbit insertion and NASA TV commentary begin 1:00 a.m. EDT on July 5 — Post-orbit insertion briefing at JPL Watch all of these events online, at: http://www.nasa.gov/nasatv http://www.ustream.tv/nasa http://www.ustream.tv/nasajpl2 Learn more about the Juno: http://www.nasa.gov/mission_pages/juno … Continue reading

Jupiter’s Gravitational Influence now the Dominant Force on the Juno Spacecraft
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As a spacecraft nears a large celestial body, there is a point where the gravitational influence of that body becomes greater than that of any other body. Jupiter has a rather large gravitational influence, and the Juno spacecraft, still over a month away from its encounter with the giant planet, has crossed that threshold. From: JPL Press Release: 2016-136: Since its launch five years ago, there have been three forces tugging at NASA’s Juno spacecraft as it speeds through the solar system. The sun, Earth and Jupiter have all been influential — a gravitational trifecta of sorts. At times, Earth was close enough to be the frontrunner. More recently, the sun has had the most clout when it comes to Juno’s trajectory. Today, it can be reported that Jupiter is now in the gravitational driver’s seat, and the basketball court-sized spacecraft is not looking back. “Today the gravitational influence of Jupiter is neck and neck with that of the sun,” … Continue reading

NASA’s Juno Spacecraft to Explore Jupiter Starting in July
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The Juno mission as been on its way to Jupiter since its launch in August of 2011, flying by Earth in October of 2013 for a gravity assist maneuver, and will arrive at the gas giant planet on July 4, 2016 at 8:35 p.m. PDT. Juno is the first solar powered mission to Jupiter, breaking the record for the most distant solar powered spacecraft in January of 2016. Why Juno? If you want to know how stars and solar systems form, and how planets behave, you have to understand Jupiter. Humans have been studying Jupiter for hundreds of years, yet we still have major unanswered questions about this giant planet: How did Jupiter form? How is the planet arranged on the inside? Is there a solid core, and if so, how large is it? How is its vast magnetic field generated? How are atmospheric features related to the movement of the deep interior? What are the physical processes that power … Continue reading

September Morning Sky, and October Conjunction
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In the past couple weeks, I’ve been asked multiple times, as has my wife from her students: “What planet is that in the morning sky?” The one high and bright is Venus. Mars is below Venus, and a little to the north – right above the bright star Regulus. Jupiter is lower, near the horizon. On 17 Oct 2015, there will be a conjunction: Mars will be 24′ from Jupiter. That’s REALLY close, and I expect to see some spectacular images of the two posted later that day. Below is an illustration of the locations of the planets during the conjunction. They may look close together in the sky from your vantage point here on Earth, but they are anything but! … Continue reading

Across the Universe: By Paper, to the Stars
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This column was first published in The Tablet in June, 2004… read the end to find out what happened! The people who design airplanes say that a plane can’t fly until its weight is matched by the weight of its paperwork. The same must be true for launching spacecraft to another planet. Last month [May 2004] I took part on a NASA panel in Washington DC, reviewing five competing plans to build a planetary probe; in the run-up to the panel I was shipped 30 pounds of paper to read. NASA’s “New Frontiers” program is a development of another project driven by piles of paperwork: the Solar System Decadal Survey commissioned by NASA and executed by the National Academy of Sciences in 2002. After hearing from hundreds of planetary scientists at meetings around the world (and reading white papers solicited and gathered by various international  societies) a committee of graybeards outlined where NASA should be spending its money over the next … Continue reading

Orbits of Jupiter’s Moons
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I was putting the finishing touches on a lecture I was to give to the Warren Astronomical Society titled “Exploring the Solar System;” I wanted to put a couple images of the orbits of the moons of the planets. The image below shows the inner moons of Jupiter, in nice circular orbits – this is pretty much exactly what one would expect when it comes to moons, right? Now, I KNEW that Jupiter had 67 moons, and I KNEW that several of them were captured comets and asteroids… but I did not expect to see this when I zoomed out to show the orbits ALL of Jupiter’s moons. Jupiter is a MESS! And Saturn isn’t any better: I don’t know WHAT I was expecting, but this wasn’t it, and it should have been… I can’t remember seeing anything like this in any books of Astronomy that I have seen. These images were captured from the Windows app Celestia – I … Continue reading