Jupiter's trademark Great Red Spot – a swirling anticyclonic storm feature larger than Earth – has shrunken to the smallest size ever measured. Astronomers have followed this downsizing since the 1930s.
"Recent Hubble Space Telescope observations confirm that the Great Red Spot (GRS) is now approximately 10,250 miles across, the smallest diameter we've ever measured," said Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Md. Historic observations as far back as the late 1800s gauged the GRS to be as big as 25,500 miles on its long axis. The NASA Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured the GRS to be 14,500 miles across.
Starting in 2012, amateur observations revealed a noticeable increase in the spot's shrinkage rate. The GRS's "waistline" is getting smaller by 580 miles per year. The shape of the GRS has changed from an oval to a circle. The cause behind the shrinking has yet to be explained.
"In our new observations it is apparent that very small eddies are feeding into the storm," said Simon. "We hypothesized that these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot."
Simon's team plans to study the motions of the small eddies and also the internal dynamics of the GRS to determine if these eddies can feed or sap momentum entering the upwelling vortex.
In the comparison images one Hubble photo was taken in 1995 when the long axis of the GRS was estimated to be 13,020 miles across. In a 2009 photo, the GRS was measured at 11,130 miles across.
Credits
NASA, ESA, and A. Simon (Goddard Space Flight Center);Acknowledgment: C. Go, H. Hammel (Space Science Institute, Boulder, and AURA), and R. Beebe (New Mexico State University)
| About The Object | |
|---|---|
| Object Name | Jupiter |
| Object Description | Planet |
| Distance | The semi-major axis of Jupiter's orbit about the Sun is 5.2 astronomical units (483 million miles or 778 million km). |
| Dimensions | The planet has a diameter of roughly 88,789 miles (142,984 km) at the equator. |
| About The Data | |
| Data Description | The Jupiter images are from HST proposals:1 995 Data: PI: R. Beebe (New Mexico State University), M. Belton (NOAO/AURA), C. Cunningham (Institute for Space and Terrestrial Science), P. Gierasch (Cornell University), A. Ingersoll (Caltech), G. Orton (NASA Jet Propulsion Laboratory), J. Pollack (NASA Ames Research Center), and K. Rages (SETI Institute) 2009 Data: PI: H. Hammel (Space Science Institute), A. Simon (NASA/Goddard Space Flight Center), T. Clarke (Boston University), I. de Pater (University of California, Berkeley), K. Noll (NASA/Goddard Space Flight Center), G. Orton (NASA Jet Propulsion Laboratory), A. Sanchez-Lavega (Universidad del País Vasco), and M. Wong (University of California, Berkeley) 2014 Data: PI: A. Simon (NASA Goddard Space Flight Center), G. Orton (NASA Jet Propulsion Laboratory), J. Rogers (University of Cambridge, UK), and M. Wong and I. de Pater (University of California, Berkeley) |
| Exposure Dates | 1995, 2009, 2014 |
| Filters | WFPC2 (1995): F410M, F555W, and F673N WFC3/UVIS (2009): FQ437N, FQ508N, and FQ634N WFC3/UVIS (2014): F395N, F502W, and F631N |
| About The Image | |
| Color Info | 1995 image: Blue: F410M, Green: F555W, Red: F673N 2009 image: Blue: FQ437N, Green: FQ508N, Red: FQ634N 2014 image: Blue: F395N, Green: F502W, Red: F631N |
| Compass Image |  |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
