When the solar system was in its infancy, about 600 million years old, the sorting out of the terrestrial or rocky planets and the giant gaseous planets had already begun. Jupiter’s orbital changes, in particular, would have a significant effect on all the other planets and computer simulations of what would happen as Jupiter shifted orbits give rise to all sorts of problems.
The inner rocky planets behave erratically with Earth colliding with either Mars or Venus. Other simulations have either Uranus or Neptune being ejected from the solar system.
Neither of these scenarios happened and, as David Nesvorny of Colorado’s Southwest Research Institute searched for an answer, he came up with the idea that five, rather than four, giant planets existed in the young solar system.
Assuming that Jupiter ejected this planet from the solar system gave Nesvorny a computer model that fits exactly with today’s planetary arrangement. He says that the hundreds of free-floating planets in interstellar space makes this a feasible explanation.
Nesvorny submitted his paper, “Young Solar System’s Fifth Giant Planet” to the Sept. 13, 2011 online issue of The Astrophysical Journal Letters.
Focus on the Planets
Mercury lies low on the eastern horizon in early May just before sunrise. This is a poor time to spot the innermost planet but it may be visible with binoculars.
Venus still dominates one-third of the way up on the northwestern horizon at sunset as May opens and remains in view until around 11:30 p.m. Venus will drop noticeably in altitude each night and, by month’s end, will be low on the horizon setting about 40 minutes after sunset.
Mars starts the month high in the south about an hour after sunset. Early in the month a 6-inch or better telescope should be able to pick up features such as the white northern polar cap but these will fade as the month progresses.
Jupiter is lost to view for much of May and rises only a few minutes before the sun at month’s end.
Saturn is high in the southeast about an hour after sunset as the month opens and is up until after midnight. The tilt of the rings, while narrower, are still open to view and a telescope will reveal the dance of its moons, particularly Titan, around the planet.
Uranus is low in the east and Neptune just above the southeastern horizon during the predawn hours late in the month. The Sky & Telescope website skypub.com/urnep will help to spot them.
1. Sunrise, 5:26 a.m.; sunset, 7:40 p.m. This is May Day or Beltane, a cross-quarter day marking the midpoint between the spring equinox and summer solstice. Mars is to the upper right of the Moon at nightfall.
5. This should be the peak night for the Eta Aquarid meteor shower however, with the peak viewing coming shortly before dawn and the close proximity of the full Moon, this will be a very poor year to view this major shower.
6. Full Moon, 11:35 p.m. The full Moon of May is called the Flower Moon, the Planting Moon, or the Milk Moon. The Moon is at perigee, or nearest approach to Earth only a half hour before it becomes full and these two facts combine to produce abnormally high tides.
7. Orange Antares of Scorpius is just to the lower left of the Moon in the predawn hours.
12. Moon in last quarter, 5:47 p.m.
13. Jupiter is in conjunction passing behind the sun and will return to the morning sky by early June. The sun enters Taurus on the ecliptic.
19. The sun is at apogee or farthest distance from Earth.
20. New moon, 7:47 p.m. The sun enters the astrological sign of Gemini but astronomically is still in Taurus.
22. Venus is to the upper right of a thin crescent moon while Betelgeuse is far to the lower left on the western horizon after sunset.
28. Moon in first quarter, 4:15 p.m. Mars is directly above the moon at nightfall.
31. The moon, Spica and Saturn form an ascending line on the southern horizon as an hour after sunset. Sunrise, 4:53 a.m.; sunset, 8:13 p.m.
Send astronomical queries to Clair Wood at firstname.lastname@example.org or care of the Bangor Daily News, Style Desk, P.O. Box 1329, Bangor 04402.