Bakersfield Night Sky – February 17, 2018
By Nick Strobel
Thursday was the first show of the William M Thomas Planetarium’s spring line-up as “Black Holes” played to an audience eager to see a beautiful star field with the Goto Chronos and take a flight through the Milky Way into the supermassive black hole at the center. This coming Thursday is “Supervolcanoes” which after a tour of the night sky will explain what happens in the most powerful eruptions on Earth (thousands of times more powerful than Mt St Helens). Supervolcanoes put so much ash, gases, and other material into the atmosphere that they can cause global mass extinctions through the very dramatic climates changes. Fortunately, these types of eruptions are rare!
Tickets are still on sale for Supervolcanoes and are also on sale for the new show “From Dream to Discovery” about the engineering it takes to build spacecraft and get them into space. Speaking of engineering, how about that SpaceX Falcon Heavy rocket test on February 6? The two side boosters made it right back to where they launched. Another step accomplished to getting people back to the Moon and finally getting to Mars.
A step toward what will be another engineering marvel was also unveiled on February 6 but it got less coverage in the U.S. than in other parts of the world. An international consortium called the Square Kilometer Array (SKA for short) is building what will be the world’s largest radio telescope with the light-gathering power of a square kilometer area telescope. It will be made of hundreds of radio dishes each 15-meters across in South Africa and thousands of the dishes in Australia.
The first prototype radio dish was unveiled on February 6 at the test site in Shijiazhuang, China where it will undergo a battery of tests. Another prototype radio dish will be assembled in South Africa in a few months for engineering tests there. Components of the system are created in ten countries [Australia, Canada, China (consortium lead), India, Italy, New Zealand, South Africa, Sweden, The Netherlands, and United Kingdom] and then assembled on-site. Besides the radio dishes, the array will also use tens of thousands of small fixed antennae in what’s called an “aperture array”. Construction of the array will begin in 2020.
All the metal fabrication and construction of SKA will be one part of the engineering problem to figure out. The other will be to how to deal with all the data it will generate. SKA’s first phase will produce some 160 terabytes of raw data per second that will be handled by supercomputers filling up large rooms. With a data rate about ten times today’s global internet traffic, this an example of a “Big Data” project.
Last week more details about the TRAPPIST-1 exoplanet system were announced. We already knew the sizes of the seven planets (all roughly Earth-size) and their orbits. Further observations revealed the masses of the planets from how they tugged on each other. Mass and size reveals the density which gives us an idea of the composition of an object. One of the planets (“e”) is denser than Earth and the others need to include a higher percentage of water than what Earth has but still less than 5% of their mass.
Other observations have shown they do not have hydrogen-rich atmospheres like Neptune but we’ll need to wait for the James Webb Space Telescope to find out what their atmosphere DO have in them and therefore, how habitable they really are. Three of the exoplanets are in the “habitable zone” where under the most basic of assumptions their surface temperatures are such that liquid water could exist but the composition and thickness of their atmospheres can greatly affect the surface temperatures. For example, Venus is on the inner boundary of the sun’s habitable zone but its thick carbon dioxide atmosphere has made it over twice as hot as it would be without an atmosphere and if Mars’s atmosphere was as thick as our atmosphere, it would be significantly warmer.
A thin sliver of a waxing crescent moon will be visible low in the west just after sunset but you’ll probably need to wait until tomorrow evening to see it more easily. Maybe, just maybe, you’ll be able to spot Venus even closer to the ground but the sunset glow coupled with the Bakersfield air will probably make that impossible until the end of the month (see the inset of the attached star chart). The moon will be at first quarter phase on February 23, so it will be high in the south at sunset. No full moon in February because January stole it for the total lunar eclipse but it will be darn close to a full moon on the last day of February.
The pre-dawn sky has the naked-eye outer planets lined up with the bright star Spica in the southern sky at 6 a.m. all roughly equally spaced from each other (see the attached star chart). Jupiter is the brilliant "morning star" in the middle of the line-up. Below Mars will be its rival in brightness and color, Antares. Which do you think is brighter?