Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brighter Neptune suggests a planetary change of seasons

16.05.2003


A progressive increase in the brightness of the planet Neptune suggests that, like Earth, the distant planet has seasons.


A time series of images of the planet Neptune taken by the Hubble Space Telescope illustrate increasing cloudiness that is a hallmark of seasonal change. The growing bands of clouds in the southern hemisphere of the planet suggest seasonal change. Because the planet takes about 165 years to orbit the sun, the seasons on Neptune last more than 40 years.
Image credit: L. Sromovsky, P.Fry (University of Wisconsin), and NASA



Observations of Neptune made during a six-year period with NASA’s Hubble Space Telescope by a group of scientists from the University of Wisconsin-Madison and NASA’s Jet Propulsion Laboratory (JPL) show that the planet is exhibiting a significant increase in brightness. The changes, observed mostly in the planet’s southern hemisphere, show a distinct increase in the amount and brightness of the banded cloud features that are a distinctive feature of the planet.

"Neptune’s cloud bands have been getting wider and brighter," says Lawrence A. Sromovsky, a senior scientist at UW-Madison’s Space Science and Engineering Center and a leading authority on Neptune’s atmosphere. "This change seems to be a response to seasonal variations in sunlight, like the seasonal changes we see on Earth."


The findings are reported in the current issue (May 2003) of Icarus, a leading planetary science journal.

Neptune, the eighth planet from the sun, is known for its weird and violent weather. It has massive storm systems and ferocious winds that sometimes gust to 900 miles per hour, but the new Hubble observations are the first to suggest that the planet undergoes a change of seasons.

Using Hubble, the Wisconsin team made three sets of observations of Neptune. In 1996, 1998 and 2002, they obtained observations of a full rotation of the planet. The images showed progressively brighter bands of clouds encircling the planet’s southern hemisphere. The findings are consistent with observations made by G.W. Lockwood at the Lowell Observatory, which show that Neptune has been gradually getting brighter since 1980.

"In 2002 images, Neptune is clearly brighter than it was in 1996 and 1998," Sromovsky says, "and is dramatically brighter at near infrared wavelengths. The greatly increased cloud activity in 2002 continues a trend first noticed in 1998."

Like the Earth, Neptune would have four seasons: "Each hemisphere would have a warm summer and a cold winter, with spring and fall being transitional seasons, which may or may not have specific dynamical features," the Wisconsin scientist explains.

Unlike the Earth, however, the seasons of Neptune last for decades, not months. A single season on the planet, which takes almost 165 years to orbit the sun, can last more than 40 years. If what scientists are observing is truly seasonal change, the planet will continue to brighten for another 20 years.

Also like Earth, Neptune spins on an axis that is tilted at an angle toward the sun. The tilt of the Earth, at a 23.5-degree inclination, is the phenomenon responsible for the change of seasons. As the Earth spins on its axis and orbits the sun during the course of a year, the planet is exposed to patterns of solar radiation that mark the seasons. Similarly, Neptune is inclined at a 29-degree angle and the northern and southern hemispheres alternate in their positions relative to the sun.

What is remarkable, according to Sromovsky, is that Neptune exhibits any evidence of seasonal change at all, given that the sun, as viewed from the planet, is 900 times dimmer than the sun as seen from the Earth. The amount of solar energy a hemisphere receives at a given time is what determines the season.

"When the sun deposits heat energy into an atmosphere, it forces a response. In the hemisphere getting the most sunlight, we would expect heating, which in turn could force rising motions, condensation and increased cloud cover," Sromovsky notes.

Bolstering the idea that the Hubble images are revealing a real increase in Neptune’s cloud cover consistent with seasonal change is the apparent absence of change in the planet’s low latitudes near its equator.

"Neptune’s nearly constant brightness at low latitudes gives us confidence that what we are seeing is indeed seasonal change, as those changes would be minimal near the equator and most evident at high latitudes where the seasons tend to be more pronounced."

Despite the new insights into Neptune, the planet remains an enigma, says Sromovsky. While Neptune has an internal heat source that may also contribute to the planet’s apparent seasonal variations and blustery weather, when that is combined with the amount of solar radiation the planet receives, the total is so small that it is hard to understand the dynamic nature of Neptune’s atmosphere.

There seems, Sromovsky says, to be a "trivial amount of energy available to run the machine that is Neptune’s atmosphere. It must be a well-lubricated machine that can create a lot of weather with very little friction."

In addition to Sromovsky, authors of the Icarus paper include Patrick M. Fry and Sanjay S. Limaye, both of UW-Madison’s Space Science and Engineering Center, and Kevin H. Baines of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.


Terry Devitt, 608-262-8282, trdevitt@wisc.edu

CONTACT: Lawrence Sromovsky, 608-263-6785, lsromovsky@ssec.wisc.edu.

Lawrence Sromovsky | EurekAlert!
Further information:
http://www.wisc.edu/

More articles from Physics and Astronomy:

nachricht Comet or asteroid? Hubble discovers that a unique object is a binary
21.09.2017 | NASA/Goddard Space Flight Center

nachricht First users at European XFEL
21.09.2017 | European XFEL GmbH

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Comet or asteroid? Hubble discovers that a unique object is a binary

21.09.2017 | Physics and Astronomy

Cnidarians remotely control bacteria

21.09.2017 | Life Sciences

Monitoring the heart's mitochondria to predict cardiac arrest?

21.09.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>