217P/LINEAR

{{Short description|Periodic comet with 8 year orbit}}

{{use dmy dates|date=April 2025}}

{{Infobox comet

| name= 217P/LINEAR

| image= Comet LINEAR 090818.jpg

| caption = The comet on 18 August 2009 by the Palomar Transient Factory

| discovery_ref =

| discoverer=LINEAR

| discovery_date= 11 July 2001

| designations= P/2001 MD7, P/2009 F3

| orbit_ref = {{cite web |title=Small-Body Database Lookup: 217P/LINEAR |url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?des=217P&view=OPC |website=ssd.jpl.nasa.gov |access-date=20 July 2023}}

| epoch= September 1, 2010 (2455440.5)

| semimajor= 3.944 AU

| perihelion= 1.224 AU

| aphelion= 6.665 AU

| eccentricity= 0.6896

| period= 7.834 a
2861.4 d

| inclination= 12.880°

| asc_node = 125.621°

| arg_peri = 246.767°

| long_peri =

| tjup = 2.548

| Earth_moid = 0.308 AU

| last_p = 16 July 2017{{cite web |title=217P/LINEAR |url=http://www.aerith.net/comet/catalog/0217P/index.html |website=www.aerith.net|accessdate= 17 August 2024}}

| next_p = 24 May 2025

| M1 = 13.8

}}

217P/LINEAR is a periodic Jupiter-family comet with an orbital period of 7.83 years. It was discovered by LINEAR on 11 July 2001.{{cite journal |last1=Blythe |first1=M. |last2=Sarounova |first2=L. |last3=Marsden |first3=B. G. |title=Comet P/2001 MD_7 (LINEAR) |journal=International Astronomical Union Circular |date=1 July 2001 |volume=7660 |pages=1 |url=http://www.cbat.eps.harvard.edu/iauc/07600/07660.html#Item1 |issn=0081-0304}}

Upon discovery the comet was diffuse. It was later identified as an asteroidal object with an estimated magnitude of 17.6 detected on 21 and 24 June 2001, again by LINEAR, that had been named {{mp|2001 MD|7}}. A preliminary orbit indicated an orbital period of 7.5 years. The comet brightened up to an apparent magnitude of 12 from November 2001 to January 2002.{{cite web |first = Gary |last= Kronk |title=C&MS: 217P/LINEAR |url=https://cometography.com/pcomets/217p.html |website=cometography.com |access-date=17 August 2024}}

The comet was recovered in images obtained remotely by Ernesto Guido, Giovanni Sostero, and Paul Camilleri in images obtained on 17 and 18 March 2009 with a remotely operated reflector telescope with an estimated apparent magnitude of around 18.2. The comet has a diffuse coma 15 arcseconds across.{{cite journal |last1=Guido |first1=E. |last2=Sostero |first2=G. |last3=Camilleri |first3=P. |last4=Marsden |first4=B. G. |title=Comet P/2009 F3 (LINEAR) |journal=International Astronomical Union Circular |date=1 March 2009 |volume=9031 |pages=1 |url=https://ui.adsabs.harvard.edu/abs/2009IAUC.9031....1G/abstract |issn=0081-0304}} In mid October, around 13.4 October, 34 days after perihelion, an outburst took place, during which the comet brightened by 1.7 – 2.3 magnitudes and an expanding dust cloud was observed. The estimated mass loss from the comet was estimated to be 10⁶–10⁹ kg, while no fragments were observed.{{cite journal |last1=Sarugaku |first1=Y. |last2=Ishiguro |first2=M. |last3=Ueno |first3=M. |last4=Usui |first4=F. |last5=Watanabe |first5=J. |title=OUTBURST OF COMET 217P/LINEAR |journal=The Astrophysical Journal |date=20 November 2010 |volume=724 |issue=1 |pages=L118–L121 |doi=10.1088/2041-8205/724/1/L118}}

The comet is a near-Earth object, with a minimum orbit intersection distance of {{convert|0.308|AU|e6km|abbr=unit}}. The comet will approach Earth to a distance of 0.396 AU on 7 September 2048. The comet also has close approaches to Mars, approaching to a distance of 0.1 AU on 12 November 1905 and an even closer approach will take place on 1 April 2056, when the comet will approach to a distance of {{convert|0.064|AU|e6km|abbr=unit}}.