This composite Hubble Space Telescope image captures the positions of Comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. On that date the comet passed by Mars at approximately 87,000 miles (about one-third the distance between Earth and the Moon). At that time, the comet and Mars were approximately 149 million miles from Earth.
The comet image shown here is a composite of NASA Hubble Space Telescope exposures taken between October 18, 8:06 a.m. EDT and October 19, 11:17 p.m. EDT. Hubble took a separate photograph of Mars at 10:37 p.m. EDT on October 18.
The Mars and comet images have been added together to create a single picture to illustrate the angular separation between the comet and Mars at closest approach. The separation is approximately 1.5 arcminutes, or 1/20th of the angular diameter of the full Moon. The background starfield in this composite image is synthesized from ground-based telescope data provided by the Palomar Digital Sky Survey, which has been reprocessed to approximate Hubble's resolution. The solid, icy comet nucleus is too small to be resolved in the Hubble picture. The comet's bright coma, a diffuse cloud of dust enshrouding the nucleus, and a dusty tail, are clearly visible.
This is a composite image because a single exposure of the stellar background, Comet Siding Spring, and Mars would be problematic. Mars is actually 10,000 times brighter than the comet, and so could not be properly exposed to show detail in the Red Planet. The comet and Mars were also moving with respect to each other and so could not be imaged simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track on the comet and Mars separately in two different observations.
The images were taken with Hubble's Wide Field Camera 3.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
Credits
NASA, ESA, J.-Y. Li (PSI), C.M. Lisse (JHU/APL), and the Hubble Heritage Team (STScI/AURA)| About The Object | |
|---|---|
| Object Name | Mars, Comet C/2013 A1, Comet Siding Spring |
| Object Description | Planet and Comet Closest Approach |
| Distance | On October 19, 2014, at 2:28 p.m. EDT, Mars and Comet Siding Spring were approximately 149 million miles from Earth and passed within 87,000 miles (1.5 arcminutes) of each other. |
| About The Data | |
| Data Description | The image was created from Hubble data from the following proposals: : PI: Z. Levay and the Hubble Heritage Team (STScI/AURA) and : PI: J.-Y. Li (Planetary Science Institute), T. Farnham and M. Kelley (University of Maryland), N. Samarasinha (Planetary Science Institute), D. Bodewits and M. A'Hearn (University of Maryland), C. Lisse (JHU/APL), W. Delamere (Delamere Support Services), and M. Mutchler (STScI). |
| Instrument | HST>WFC3/UVIS |
| Exposure Dates | October 19, 2014 |
| Filters | F775W |
| About The Image | |
| 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. |
