May 26, 2019

Extrasolar planet spotted in transit

Until recently the major evidence for planets circling other stars has been anomalies in their orbits. Now an extrasolar planet has been caught in the act of transiting, or passing across the face of, its star.

Two teams of astronomers have independently confirmed that the dimming of a star located 150 light-years away in the constellation Pegasus was caused by an orbiting planet blocking the star’s light from Earth. The planet is an extremely large gas giant orbiting at only one-eighth of Mercury’s distance to the sun. It is one-third larger than Jupiter but, since it is largely made up of hydrogen, weighs only two-thirds as much. “It couldn’t possibly be a giant terrestrial planet,” said Adam Burrows, discounting any possibility that it could bear any resemblence to Earth.

Focus on the planets

The celestial show in March takes place on the evening western horizon where Mars, Jupiter, and Saturn inch ever closer together as the month unfolds.

Mercury does not make an appearance until midmonth when the faint planet might be glimpsed above Venus in the brightening morning sky with the aid of binoculars.

Venus rises about an hour before sunrise low on the southeastern horizon. In a telescope, Venus will appear almost fully illuminated but quickly fades in the strengthening daylight. Venus is located to the left of the crescent moon on March 3.

Mars, Jupiter and Saturn may be treated as a single grouping this month as they form an ascending diagonal line in that order on the western horizon about an hour after sunset. Starting around March 8, check out these three planets nightly as they move ever closer together. By month’s end, Jupiter and Saturn will be at their greatest proximity in the past 20 years.

Uranus and Neptune are pretty much a lost cause in March, according to Fred Schaaf of Sky & Telescope, who writes that they lie about a half-degree from Venus early in the month giving a challenge to viewers with both powerful telescopes and finder’s charts. Note that the moon passes less than a degree south of Neptune and Uranus on March 30 and 31, respectively.

Pluto is high in the south during the predawn hours, giving an additional challenge to those who come out early to watch for Uranus and Neptune.

Focus on a constellation

Low on the southeast horizon in March is the rather obscure constellation of Crater the Cup. Shaped roughly like the five sides of an octagon perched on a pedestal, Crater has been mentioned as the drinking cup for such gods as Apollo, Bacchus, Hercules and Achilles. In one Greek legend, Crater is the cup of Dionysus, the god of wine and merriment, who carried it with him throughout the known world as he introduced the “fruit of the vine” to everyone he met. In fact, all of the legends of Crater have it as the focal point for a subject dear to the hearts of the ancients — rich, red wine! One source claims that the early Christians referred to Crater as being the Holy Grail that Jesus used at the Last Supper and then was placed in the heavens for safekeeping. There are no major stars in Crater and, in fact, at least one major book of constellations fails to mention it at all.

March events

1 Sunrise, 6:14 a.m.; sunset, 5:22 p.m. 6 New moon, 12:18 a.m. 8 The western sky offers a dazzling array of attractions tonight with three planets joined by a crescent moon along with several bright stars. Start your nightly monitoring of the planets tonight. 11 The sun enters the constellation of Pisces on the ecliptic. Look for Aldebaran to the upper left of the moon. 12 Moon in first quarter, 1:59 a.m. 14 Moon at perigee or closest approach to Earth. 15 The Ides of March, a tough day for Julius Caesar. 17 St. Patrick’s Day. Regulus, a harbinger of spring, shines to the right of the moon tonight. 20 Full moon, 1:44 p.m. The full moon of March is the Sap Moon, Crow Moon or Lenten Moon. The spring or vernal equinox occurs at 2:35 a.m. This is the point when the sun crosses the celestial equator back into the Northern Hemisphere. The sun enters the astrological sign of Aries even though, astronomically, it is still in Pisces. 25 Early risers have the opportunity to look for red-orange Antares below the moon at dawn. 27 The moon is at apogee or farthest distance from the Earth. 28 Moon in last quarter, 7:23 p.m. 31 Sunrise, 5:19 a.m.; sunset, 6:01 p.m. If these times seem odd, remember we spring ahead an hour to daylight-saving time on Sunday.

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